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Mindat Mineralogy Messageboard - Best Minerals K http://www.mindat.org/msgboard-77.html Mon, 20 May 2013 17:37:01 +0000 Phorum 5.2.15a http://www.mindat.org/forum.php?read,77,273124,273124#msg-273124 Kermesite (5 replies) http://www.mindat.org/forum.php?read,77,273124,273124#msg-273124 Best Minerals K and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.

Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?

Kermesite
Sb₂S₂O


Kermesite, ~18cm wide	©

Kermesite is a somewhat rare antimony mineral currently (2012) with slightly more than 200 localities listed here on Mindat. It was first discovered in Freiberg, Germany in 1730 but was not described until 1832 by Beudant from French material. It is closely related to stibnite with which it sometimes is associated. In many cases it has been formed by the oxidation of stibnite, but under the right conditions it can form as a primary mineral. The first x-ray diffraction patterns were done by Wolfe at Harvard in the 1930s, but because of the complex nature of the patterns, probably due to twinning. He never published his results, but only Professor Palache of Harvard who eventually reported them in his edition of the Dana system. In the early days of mineral collecting, probably the best kermesite specimens came from Bräunsdorf, Freiberg District, Saxony, Germany. Some years later, perhaps ~1940 the amazing kermesites from the Globe and Phoenix Mine at Kwekwe, Zimbabwe were found. Now, rivaling anything found in Zimbabwe are the new Chinese kermesites from Dafeng, Guangxi. I tend to favor the old ones from Zimbabwe as the best but some think the new Chinese ones (2000?) are better. Unfortunately, we don't yet have any images of the best of the new Chinese specimens, but what we do have will allow you to imagine what the best ones might look like. The new Chinese specimens are much shinier than the ones from Zimbabwe, but they have only been out of the ground for a short time and only time will tell how long they stay shiny. Many sulfides loose their luster, some faster than others. A lot depends on the conditions they endure during storage. Pyrite will remain shiny for a long time unless you put it out in the weather and then an a few months or years it will loose its luster.

Small crystals of kermesite are red, but when they get thicker, they appear almost black with just a hit of red here and there. When the first kermesites were found in China, they were thought to to be not very good clusters of stibnite crystals and were sold in the mineral market in Changsha for only a few dollars each. It was soon discovered that they were kermesite and possibly the finest specimens known of the species and the prices went from a few dollars each to hundreds and thousands of dollars each. So if you encounter a cheap low grade stibnite cluster with just a hint of red, buy all of them you can get.
[Rock Currier 2012]

Kermesite
Canada
Québec, Centre-du-Québec, Arthabaska RCM, Saints-Martyrs-Canadiens, Lac Nicolet Antimony mine (Quebec Antimony mine; South Ham Antimony mine; Lac Nicolet mine)


Kermesite 3.2cm wide	© Michael C. Roarke

Kermesite
China
Guangxi Zhuang Autonomous Region, Nanning Prefecture, Shanglin Co., Dafeng, Kermesite occurrence


Kermesite on Stibnite 5cm wide	© JF Carpentier


Kermesite on Stibnite 5cm wide	© fabreminerals.com


Kermesite 9.8cm tall	© fabreminerals.com


Kermesite & Stibnite 7.5cm tall	© fabreminerals.com


Kermesite 11.2cm tall	© fabre


Kermesite & Gypsum 8.8cm tall	© fabreminerals.com

Specimens from this occurrence were first offered for sale by some of the dealers in Changsha, China. Changsha, China is the capitol of Hunan, China. They were first sold as clusters of stibnites, but were soon identified by the geological survey as being the much rarer mineral kermesite. Several hundred specimens were eventually produced by the mine. Some were associated with stibnite as well as senarmontite and the rare mineral pääkkönenite. Some crystal sprays approach 20 cm in diameter. The ones shown here are rather modest examples, but when better specimens are posted, we will include them here.

Kermesite
Czech Republic
Bohemia (Böhmen; Boehmen), Central Bohemia Region, Příbram


Kermesite 4.8cm tall	© Weinrich

Kermesite
Germany
Saxony, Erzgebirge, Freiberg District, Bräunsdorf, Neue Hoffnung Gottes Mine


Kermesite & Quartz ~7cm tall	©


Kermesite ~10cm tall	©

Kermesite
Slovakia
Bratislava Region


Kermesite 5.6cm wide	© Norman King

Kermesite
Slovakia
Bratislava Region, Pezinok Co., Pezinok


Kermesite 3.4cm tall	© Rob Lavinsky


Kermesite 6.5cm tall	© Dan & Diana Weinrich Minerals


Kermesite 13cm wide	© Laco Turecky


Kermesite 8.5cm tall	© Kristalle and Crys


Kermesite 3.82cm wide	© Jasun McAvoy


Kermesite 7.8cm wide	© Rob Lavinsky

Kermesite
Slovakia
Bratislava Region, Pezinok Co., Pezinok, Kolársky hill, Nová Alexander adit


Kermesite 25cm wide	© Karsten Ivan

Kermesite
Slovakia
Bratislava Region, Pezinok Co., Pezinok, Kolársky hill


Kermesite 9.5cm wide	© fabreminerals.com


Kermesite 15cm tall	© Laco Turecky

Kermesite
Zimbabwe
Midlands, Gweru (Gwelo) District, Kwekwe (Que Que), Globe and Phoenix Mine (Phoenix and Globe Mine


Kermesite ~7.5cm tall	©


Kermesite ~12cm tall	©


Kermesite ~7.5cm tall	©

The Globe and Phoenix Mine was in its hay day a large thriving gold mine. When George Burnham visited there in 1950 he was told hat he was about 10 years too late to get any kermesite specimens and came away with only a few specimens that were lying around the camp. But all told, the mine must have produced several hundred specimens.

[Rock Currier, 1 edition 2012]

Click here to view Best Minerals K[/url] and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.]]> Rock Currier Best Minerals K Mon, 08 Oct 2012 17:59:33 +0000 http://www.mindat.org/forum.php?read,77,256346,256346#msg-256346 Katophorite-series (1 reply) http://www.mindat.org/forum.php?read,77,256346,256346#msg-256346 First Draft

Click here to view Best Minerals K , and here for Best Minerals A to Z and here for Fast Navigation for finished Best Minerals articles.

Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?

The katophorite series minerals are minerals in the amphibole group, see Amphibole Group main article for an overview of the group. The series contains the following minerals:

Ferrikatophorite
Na(NaCa)(Fe2+₄ Fe3+) (Si₇Al) O₂₂(OH)₂

Fluor-magnesiokatophorite
Na(NaCa)(Mg₄ Al) (Si₇Al) O₂₂F₂

Katophorite
Na(NaCa)(Fe2+₄ Al) (Si₇Al) O₂₂(OH)₂

Magnesioferrikatophorite
Na(NaCa)(Mg₄ Fe3+) (Si₇Al) O₂₂(OH)₂

Magnesiokatophorite
Na(NaCa)(Mg₄ Al) (Si₇Al) O₂₂(OH)₂

Unnamed (K-analogue of Magnesioferrikatophorite)
K(NaCa)(Mg₄ Fe3+) (Si₇Al) O₂₂(OH)₂


Magnesiokatophorite 85mm crystal	© David K. Joyce

The katophorite-series minerals are intermediate in composition between the richterite series (Si₈ in the T position) amphiboles and the taramite series (Si₆Al₂ in the T position), and between the edenite (Ca₂ in the B position) and arfedsonite (Na₂ in the B position), and may be found together with minerals from these series. It should also be realized that for all of katophorite minerals listed above, only katophorite and magnesiokatophorite are formally approved by IMA, all the others are in the "Named" category

Katophorite minerals are normally found in alkaline intrusions, such as nepheline syenites and also lamproites and similar rocks, typically together with other Sodium and Calcium bearing amphiboles. The Khibina massif in Russia is infamous in this respect, as 25 different amphiboles has been identified there.

The best katophorite crystals are those from the Bear Lake diggings in Ontario, Canada, where giant, well formed crystals exceeding a foot in length can be found in the calcite vein-dykes. It should be noted that also here more than one amphibole-series is present, and some of the (fluoro)magnesiokatophorites from Bear Lake will undoubtedly be richterites or even edenites.

The Norwegian magnesiokatophorites from the Larvik plutonic complex is also quite good for an amphibole.

Magnesiokatophorite
Canada
Québec , Abitibi-Témiscamingue, Témiscamingue RCM, Les Lacs-du-Témiscamingue, Kipawa alkaline complex


Magnesiokatophorite 2,7cm specimen	© JSS

The Kipawa Syenite Complex id a less than 200 m thick kataphorite-aegirine syenite of probable metasomatic origin. It can be traced for more than 50 krn near the Kipawa river. Large crystals and crystalline aggregates of katophorite are found with albite, potassium feldspar, nepheline and aegirine near the boundary between the syenite and the overlaying "red pine chute" gneiss. Along its lower margin, a 1300 m long by 5 m thick consists of diopside and magnesiorichterite-rich schist with large amounts of eudialyte, agrellite and other rare minerals, Also pargasite and tremolite are found in the Kipawa rock sequence. Apparantly, the amphiboles from here can be identified from their associated minerals.

Literature:
Kenneth L. Currie, Otto Van Breemen (1996): The origin of rae minerals in the Kipawa syenite complex, Western Quebec. The Canadian Mineralogist Vol 34 pp435-451

Magnesiokatophorite ?
Fluormagnesiokatophorite

Canada
Ontario , Haliburton Co, Monmouth Township, Gooderham, Bear Lake diggings (Gibson Road Western occurrence)


Magnesiokatophorite 3cm specimen	© Andrew Johns


Magnesiokatophorite 6,1cm specimen	© M.Adamowicz


Magnesiokatophorite up to 20mm crystals	© Tim Jokela


Fluormagnesiokatophorite up to 7,8cm crystal	© Norman King

The Bear Lake diggings is a pay pr. dig mineral collecting site operated by the Bancroft Chamber of Commerce. According to their statistics, several hundred collectors visit the site every year. They are looking for apatite, large mica schists and amphiboles in sub-parallell, steep and up to 2-3m wide weathered calcite vein-dykes. There are several field trip reports avaible on the net, one of them also on Mindat, see Michal Adamowicz’s article giving directions and advice for where and how to collect.

The calcite veins-dyke complexes are predominantly of metacarbonatitic origin, but also calc-silicate veins of a metasedimentaty origin can be found in this area.

The mineralogy of metasedimentary and metacarbonatite calcite veins are not very different, but Moecher et. al (1997) lists the following characteristics for Ontario calcite vein-dykes of carbonatitic origin, such as those found at the Bear Lake diggings:
- The calcite is often of pinkish-orange color
- Green/blue/colorless fluorapatite communly constitutes a large (up to 20 modal%) portion of the rock
- Small apatite grains embedded in mica often contains sufficient U/Th to form halos.
- Zircon and allanite are common accessory minerals.

Hawthorne et.al (2006) provides detailed analytical data for 4 amphiboles “representative for the suite of the locality”. 3 of the 4 are of metacarbonatitic origin, One of these was a fluororichterite and 2 were fluoromagnesiokatophoites. The 4th amphibole was a fluorotremolite of metasedimentary origin. The Ontario Ministry of mines refers to the amphiboles from the calcite vein-dykes as “edenite”, using “Berry, J.E.; Evidence for the Petrogenesis of a Calcite vein-Dyke Complex, bear Lake Diggings, Monmouth Township, Ontario, Canada” as a reference, which unfortunately I have no access to.

The data provided by Hawthorne et.al(2006) shows that
- All analysed samples had Mg>>Fe 2+ in the C position
- The analysed fluororichterite has a composition near the fluoroedenite-fluororichterite border line
- The F/OH ratio is variable and not all amphiboles from the Bear Lake diggings will necessarily be F dominant
- The Fe2+/Fe3+ratio is relative consistant at 2:1
- The amphiboles are Na rich, all with Na>0,5 in the A position

From this it seems that the "correct" naming of the amphiboles in the apatite bearing calcite vein dykes should be “Fluorine-rich amphiboles of a edenite-richterite-magnesiokatophoritic composition”, although fluoromagnesiokataphorite is a horribly long name in it’s own right.

Literature:

David P. Moecher, Eric D. Anderson, Claudia A. Cook, and Klaus Mezger(1997): The petrogenesis of metamorphosed carbonatites in the Grenville Province, Ontario, Can. J. Earth Sei. Vol. 34

Frank C. Hawthorne, Roberta Oberti, Robert F. Martin (2006): Short-range order in amphiboles from the Bear Lake diggings, Ontario. The Canadian Mineralogist Vol 44 pp1171-1179

Magnesiokatophorite
Norway
Vestfold, Sandefjord, Vesterøya , Framnes, Rødsåsen


Magnesiokatophorite 7 cm crystal	© K.E.Larsen

The Vesterøya localities lies in the Larvik plutonic complex, which is a intrusion of larvikites and nephelinsyenites related to the permian rifting in the Oslo graben. Vesterøya lies in a semicircular, wedge shaped body of nepheline bearing larvikite. Magnesiokatophorite are found in up to 10 cm well developed crystals in coarse grained, pegmatittic rocks embedded in feldspar and associated with fluoroapatite and bastnasite-(Ce).

Larsen (1995,1998) presents a summary of 28 analysis performed on amphiboles from the Larvi plutonic complex, and finds a gradual enrichment of sodium, magnesium and ferric iron from the ferroedenites of the western part of the pluton, through hastingsite in the sentral part to the magnesiokatophorites in the eastern part of the complex.

Literature:

Larsen, Alf Olav (1995): Identiteten til de sorte amphibolene fra Oslo-feltets syenittpegmatitter. Norsk Bergverksmuseum Skriftserie, Vol 11
Larsen, Alf Olav (1998): Revisjon av nomenklatur for de sorte amfibolene fra Oslofeltets syenittpegmatitter. Norsk Bergverksmuseum Skriftserie, Vol 14
Larsen Alf Olav ed. (2010): The Langesundfjord, History, Geology, Pegmatites, Minerals. Bode Verlag.

Magnesiokatophorite
Norway
Vestfold, Sandefjord, Vesterøya , Framnes, Husebyåsen prospect


Magnesiokatophorite 3 cm crystal	© A. Michalsen

Magnesiokatophorites are found in an old abandoned feldspar quarry.

Magnesiokatophorite
Norway
Vestfold, Sandefjord, Vesterøya , Framnes, Husefjell


Magnesiokatophorite 9x6 cm specimen	© Svein A. Berge

Another location for magnesiokatophoite on Vesterøya.

Katophorite
Portugal
Azores District , San Miguel Island , Água de Pau volcano (Fogo volcano)


Katophorite 2,4mm FOV	© L.C. 2012

Água de Pau is a relatively recent volcano. The last eruption was some 5000 years ago when trachytic lavas surfaced. This lava flow contains abundant syenite clasts. These syenite clasts are of two types, silica (over)saturated and silica understaurated. in particular the undersaturated ones have scientific interest as a variety of rare minerals has been found in them. NaCa amphiboles are found as up to 5mm large grains and crystalline masses in both types of syenites. In the silica saturated syenites, the amphobole is (ferro)richterite, whereas katophorite with rims of ferrorichterite is found in the silica undersaturated syenites.

Literature

F. Rudolfi, A Renzulli, P. Santi. B.G.J. Upton (2003): Evolutionary stages of crystallization of weakly peralkaline syenites: evidence from ejecta in the plinian desposits of Agua de Pau volcano (Sao Miguel, Azores Islands): Mineralogical Magazine, Vol. 67(4), pp. 749–767

Magnesioferrikatophorite
Russia
Northern Region, Murmanskaja Oblast', Kola Peninsula, Mt, Khibiny Massif, Kukisvumchorr Northeast slope


Magnesioferrikatophorite 12mm FOV	© Pavel M. Kartashov

The Khibina massif is situated in the central part of the Kola Peninsula in the north-west corner of Russia. It is a dome-shaped mountain massif consisting of a wide range of alkaline rocks and carbonatites. The Khibina massif is somewhat a Mecca for mineralogists and mineral collectors due tonumerous pegmatites comprising unique assemblages of rare minerals. About 80 new minerals were first discovered in the Khibina and most of them occur in pegmatites and late hydrothermal veins.

Katophorite minerals are amongst the 25 different amphiboles described from the Khibina massif, so unless analytical data or mineral association leads in a very specific direction, it is difficult to assign a name to these amphiboles.

Amphiboles with intermediate composition between richterite-series and katophorite-series minerals are found as a primary amphibole in nepheline syenites, often together with secondary arvfedsonite. The katophorite bearing rocks are normally quite fine-grained and the 1,2cm, well developed crystal from Kukisvumchorr appears to be a very good kataphorite-series specimen from the Khibina massif.

Literature:
Andrei Arzamastsev, Victor Yakovenchuk, Yakov Pakhomovsky & Gregory Ivanyuk(2008): The Khibina and Lovozero alkaline massifs: Geology and unique mineralization. Field guide 33 IGC excursion No 47, July 22 – August 2, 2008

Gregory Ivanyuk, Victor Yakovenchuk, Yakov Pakhomovsky, Natalya Konoplyova, Andrei Kalashnikov, Julia Mikhailova and Pavel Goryainov (20??): Self-Organization of the Khibiny Alkaline Massif (Kola Peninsula, Russia). Earth Scienses

Ferrikatophorite
Russia
Northern Region, Murmanskaja Oblast', Kola Peninsula, Khibiny Massif, Olenii Creek (Olenii Ruchei; Oleny Ruchei)


Ferrikatophorite	© Pavel M. Kartashov

This is one of the katophorite localities in the Khibiny Massif.

Magnesiokatophorite
Russia
Northern Region, Murmanskaja Oblast', Kola Peninsula Kovdor Massif, Kovdor Phlogopite mine (Mica Mine; Slyuda Mine; Kovdorslyuda Shaft)


Magnesiokatophorite 12mm FOV	© Pavel M. Kartashov

The Kovdor phlogopite mine has been worked for phlogopite since 1963. Giant phlogopite sheets occurs with huge (up to 2m across) diopside crystals and forsterite associated by apatite. The main ellipsoid phlogopite lode is about 250x100 m at +174 m mine level, and smaller veins and nests of these phlogopite rocks penetrate the surrounding rocks. The origin of this occurrence has been discussed over the years, and both skarn-like, metasomatic and pegmatitic processes has been suggested, but it seems like this unique locality is a “peculiar alkali-ultrabasic pegmatite…. formed by successive crystallization of minerals from the margins to the center of relatively closed chambers occupied by magma” (Krasnova 2001).

Amphiboles are formed by late metasomatic action on the pegmatite, typically as tremolite-richterite-amphiboles as an alteration product of diopside. This magnesiokatophorite also appears to originate from near the contact zone between the pegmatite and surrounding rocks.

Literature:

Natal’ya I. Krasnova (2001): The kovdor phlogopite deposit, Kola Peninsula, Russia. The Canadian Mineralogist Vol. 39, pp. 33-44

Click here to view Best Minerals K , and here for Best Minerals A to Z and here for Fast Navigation for finished Best Minerals articles.]]> Olav Revheim Best Minerals K Mon, 26 Mar 2012 19:12:29 +0000 http://www.mindat.org/forum.php?read,77,224280,224280#msg-224280 Kaersutite-series (32 replies) http://www.mindat.org/forum.php?read,77,224280,224280#msg-224280 First Draft

Click here to view Best Minerals K , and here for Best Minerals A to Z and here for Fast Navigation for finished Best Minerals articles.

Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?

The kaersutite series minerals are minerals in the amphibole group, see Amphibole Group main article for an overview of the group. The series contains the following minerals:

Ferrokaersutite
NaCa₂(Fe₄Ti)(Si₆Al₂)O₂₂(OH)O

Kaersutite
NaCa₂(Mg₄Ti)(Si₆Al₂)O₂₂(OH)O

Ferrikaersutite
NaCa₂(Mg₃Fe³⁺Ti)(Al₂Si₆O₂₂)O₂


kaersutite, Qaersut, 8,0cm FOV	© Riksmuseet Stockholm

The kaersutite series minerals are a mineral group typical for the upper mantle. It is common, even a major constituent of alkali-magmas under high pressures between 25-35 kbar. On surface it can be found as sub mm grains in alkaline volcanic rocks, such as basanites and mugearites, or in alkaline plutonic rocks. Under certain circumstances, titanian amphiboles can also be formed at lower pressures, and it seems as the presence of F^- may increase the stability field of kaersutitic amphiboles even at close to atmospheric pressure.

Sometimes, the magma can fractionate and allow larger crystals to form. It is believed that this is a very slow process, taking maybe thousands of years under constant pressue and temperature to form a 1 cm crystal. The crystal then has to be transported to the surface to be frozen as a crystal (megacryst, porfyroblast) in a fine grained volcanic matrix. The long time it takes to form a large kaersutite-series mineral makes the large, well developed crystals from some of the Czech locations truly remarkable.

Kaersutite series minerals may also be fomed in volcanic dikes. This is the case for the type locality Qaersut and also some of the other localities listed in this article. In these cases, the kaersutite-series minerals grow rather rapidly, only 25 days is estimated for the up to 4 in. long crystals found near the Hoover Dam in the US. The mechanisms causing the growth of large kaersutite crystals in these dikes has been compared to how pegmatites are formed. The Qaersut occurance has sometimes been referred to as a "kaersutite-pegmatite".

The Kaersutite-series minerals are difficult to deal with, even for an amphibole group series. The chemistry, the kaersutite minerals differs from most other amphibole minerals in that one of the space groups in the C position occupied by Titanium, a ⁴⁺ cation. Kaersutite and ferrokaersutite are the only minerals ( except obertiite) in the amphibole group with a ⁴⁺ cation in the C position as a part of the chemical formula. To compensate for this added charge on the cation side, one of the two OH positions is occupied by an O^2- anion, thus balancing the formula.

The difficulties with the kaersutite series of minerals is related to the Ti cation. Normally, the actual composition of kaersutite is not very near the ideal end member formula presented at the top of this page. As for all amphiboles, the actual composition tends to be intermediate between different amphibole mineral species. This is particularily true for the position ideally filled with Ti ⁴⁺ cations. In order to qualify as a kaersutite, this position must contain more than 50% Ti , or Ti > 0,5 afu ( atoms pr. formula unit).

For most of the locations where kaersutite is known, the Ti content varies randomly between 0,3 and 0,7 afu, or in other words, the actual mineral varies randomly between pargasite and kaersutite. There are no way to tell the difference without a quantitative chemical analysis for the individual crystal, Even within the same location, the same rock, or even within the same crystal, this variation takes place. This can be illustrated from a location near Montreal, Canada, where titanian pargasite crystals had a thin coating of kaersutite.

As a consequence of this, we have the situation that there are several locations that produce nice kaersutite crystals, but also equally nice titanian pargasites. These two minerals cannot be distinghished from each by other means than a quantitive chemical analysis of the individual crystal. Since kaersutite is the rarer mineral of the two, titanian pargasites are often mislabeled as being kaersutite.

I have struggled on how to deal with this in this article. For all entries, it can be documented through reliable quantitative analytical data that kaersutite crystals with an identical appearance to those uploaded to the database can be found. There are however none of the uploaded specimens that are accompanied with analytical data proving that the individual cystal contains sufficient Ti to qualify as kaersutite. In these cases, I have followed the recommenations from the IMA Amphibole Subcommittee and used the term kaersutitic amphibole in the photo captions thus including true kaersutite, titanian pargasite, titanian magnesiohastingsite, and possibly also other closely related titanian amphiboles.

The kaersutite-series amphiboles are not particulary sought after by collectors, whether museums or private, as they are rarely much for the eye, and notoriously difficult to identify. For petrologists and scientists with an interest in mantle processes or special volcanic events, kaersutitic amphiboles are more interesting, and there is quite a lot of litterature available describing the genesis and chemistry of these amphiboles. Kaersutitc amphiboles are also much studied to understand the relationsship between ferrous and ferric iron as well as the role of Titanium in the amphibole molecule. It is also this relationsship that accounts for the variations distinguishing between kaersutite and ferrokaersutite, with ferrokaersutite being the rarer of the two.

Literature:

MCCUBBIN, Francis M.1, NEKVASIL, Hanna1, LINDSLEY, Donald H.1, and HANSKI, Eero J.(2006): NEW INSIGHTS INTO USING KAERSUTITE (TI-RICH AMPHIBOLE) AS A PETROGENETIC TOOL: AN EXPERIMENTAL INVESTIGATION, Paper No. 118-18, Philadelphia Annual Meeting

M. Darby Dyar, Stephen J. Mackwell, Ann V. McGuire, Laura R. Cross, J.David Robertson (1993): Crystal chemistry of Fe3+ and H+ in mantle kaersutite: Implications for mantle metasomatism, American Mineralogist, Volume 78, pages 968-979

Allison B. Connor (2000): THE MINERAL KAERSUTITE AND ITS OCCURRENCES, Senior thesis,Ohio State University

Kaersutite
Australia
Victoria, City of Greater Geelong , Anakie,Mount Anakie


kaersutitic amphibole, 4,2cm crystal	© Judy Rowe

Mount Anakie belongs to the Newer Basalt Province in Victoria and South Australia. This province hosts a large variety of magma types, seemingly without any clear compositional progression. Some of the magmas are characterized by the occurrence of megacrysts in the form of sometimes “unusually large crystals”, believed to have formed in fractionation of liquid magma in mantel conditions.

Mount Anakie is the largest and northernmost of 4 aligned eruption points over a distance of 5km and is considered the most interesting of these scoria cones due to the presence of kaersuite megacrysts in nepheline mugearite host rock.

I have not found any maximum size for the kaersutite.

An analysis published in "Rock forming minerals, Volume 2" shows a Ti content of 0,632 afu (5,8%wt).

Literature:

J.F.G. Wilkinson and H.D. Hensel (1991): An analcime mugearite- megacryst association from north-east New South Wales: implications for high pressure amphibole dominated fractionation of alkaline magmas.
Contrib Mineral Petrol

Irving, A. J. (1974): Megacrysts from the Newer Basalts and Other Basaltic Rocks of Southeastern Australia. Geological Society of America Bulletin 85, 1503-1514.

Kaersutite
Czech Republic
Bohemia (Böhmen; Boehmen), Ústí Region, Bílina (Bilin), Lukov u Bíliny (Lukow)


Kaersutitic amphibole 1,8 cm wide crystal	© Jakub Jirásek

Macroscopic (>2 mm) kaersutite phenocrysts can be found at several locations in the area, reaching sizes up to several cm mostly in the alkaline basaltic rocks, and kaersutitic amphibole is found in more than 70% of the more than 1000 alkaline dykes radially arranged to the main volcanic centre of the Ceske stredohori,

J. Ulrych has kindly provided analytical data from Lukov and several other locations related to the České Středohoří Mts. volcanic centre. The Ti content ranges from 4.24-5.29wt% placing these amphiboles at or near the titanian pargasite-kaersutite borderline of 0.5 pfu Ti.

Literature:
Bilina town association of Nature Sciences
Personal communication . J. Ulrych and M. Fillippi, Institute of Geology, Academy of Sciences of the Czech Republic, or shortened Institute of Geology, Acad. Sci. CR

Kaersutite
Czech Republic
Bohemia (Böhmen; Boehmen), Central Bohemia Region, Nymburk District, Seletice (Sulotice; Sulotitz; Sulloditz)


Kaersutitic amphibole 3cm	© M. Filippi and P. Magdík


Kaersutitic amphibole 3,5cm crystal	© M. Filippi and P. Magdík

Several locations near the Suletice village was described by Hibsch (1934). He is listing references back to 1903 for kaersutitic amphibole, but the knowledge of these localities may predate even these early references.

“Plundrichs Kuppe” Hill

The Plundrichs Kuppe Hill locality (SE of Suletice) is one of many locations for kaersutitic amphibole of the Ceske Stredohori Mts. Hornblendes are concentrated especially in the marginal porous part of the basaltic body.
Free kaersutitic amphibole and clinopyroxene crystals (“augites”) were collected in 1970’s on the fields below the Plundrich’s Kuppe Hill near the road to Homole village. The size of perfect columnar crystals of kaersutitic amphibole are up to 2.5 cm.

“Mückenhübel” ( Mückenkübel, Mickenhübel)
The Mückenhübel locality (ESE of Suletice) is one of the most traditional localities of kaersutitic amphiboles and clinopyroxenes (“augites”) up to more than 1 cm large in the Ceske Stredohori Mts.They originate from the tuffaceous (?) marginal part of a tephritic flow (Hibsch 1934).

The locality Mückenhübel was lost for a long time, but it was re-discovered by a coincident in 1996, when amphibole crystals was found in soil outside badger burrows. A more systematic approach revealed well formed crystals of kaersutititc amphibole and clinopyroxenes in tuff outcrops in a 20 by 40 m area. The amphibole crystals are unevenly distributed in the rock.

The amphibole is, at this location much more common than clinopyroxene and also reaches larger sizes. The size of the crystals varies from several mm to 2 cm, rarely up to 3-4 cm. In contrast, the size of clinopyroxene crystals exceeding 1 cm.

This is currently one of the more productive locations for kaersutitic amphibole and recent specimens from here are represented in collections across the central Europe.

In addition kaersutitic amphibole crystals can be found in other localities near Suletice ( 5-20km away), such as:

- Kostomlaty pod Milesovkou (up to 7 cm large crystals but often quickly disintegrating) in altered dyke (about 10 m) exposed in an abandoned coal pit

- Holomer in Usti nad Labem in altered volcanic breccia of a volcanic chimney

- Lukov, see separate entry.

- Kaersutiteic amphiboles occur commonly in phenocrysts (2 to 30 mm) of prevailing part of alkaline dyke rocks (lamprophyre, semilamptrophyre, leucocratic deravatives as bostonite) forming swarms (~1000 dykes) radially arranged to the main intrusive centre of the Ceske Stredohori Mts. in Roztoky (e.g., Techlovice and Dobkovice quarries)

Literature:

Hibsch JE (1934): Die Minerale des Böhmischen Mittelgebirges .- Gustav Fischer Verlag, Jena, 196 p.

Radon M. (1996): Current status of some sites of zeolites in the Czech Central.- Mineral, IV, 2, 85-89.

Cajz V (2003): Dyke Swarm Pattern and Tectonics in the České Středohoří Mts. Volcanic Centre, Ohře (Eger) Rift, Central Europe (Starting Points for Further Research). - Geolines, 15, 15/22.

M. Fillippi: [home.gli.cas.cz] (Mückenhübel locality only)

Kaersutite
Czech Republic

Bohemia (Böhmen; Boehmen), Plzeň Region, Černošín (Tschernoschin), Vlčí hora


Kaersutitic amphibole 3cm wide crystal group	© M. Filippi


Kaersutitic amphibole 18 cm crystal	© M. Filippi


Kaersutitic amphibole 10 cm crystal	© M. Filippi

“The Vlčí Hora Hill (704 m) locality by Černošín close to Stříbro is a complex volcanic body in Western Bohemia formed in Miocene (11.7 Ma).

Two coexisting cogenetic volcanic series have been recognized in the broad area of West Bohemia : (i) weakly alkaline series basanite – trachybasalt – (basaltic) trachyandesite – trachyte – rhyolite (15.9-11.4 Ma) and (ii) strongly alkaline series olivine nephelinite – tephrite (16.5-8.3 Ma).

Vlčí Hora Hill belongs to the weakly alkaline series, and kaersutitic amphibole has been found both in basanitic rocks (prevalenty xenocrysts) and their tuffs (free perfect crystals) often together with clinopyroxene (“augite” de facto diopside) crystals. Smaller crystal of kaersutite occur also in near village Resanov in breccia filling of a chimney. Phenocrysts of kaersutite occur also in trachyandesitic rocks of the weakly alkaline series.

It is the quantity, size and development of kaersutitic amphibole and clinoporyxene crystals that has made this location known by collectors and scientists alike. Perfectly developed ,slightly molted and pitted kaersutitic amphiboles in sizes up to 15 cm has been found, normally rimmed by clinopyroxene and titanian magnetite. Kaersutitic amphibole is usually found as single crystals, however, random intergrowths of several crystals may be found.

The kaersutitic amphiboles from Vlčí Hora is amongst the most oxidized amphiboles known, with Fe3/Fe2 ratios between 7-37. They are also rich in titanium, containing between 4.28-4.63 wt% thus being intermediate between ferroan-oxypargasite and kaersutite with both minerals present. It is very tempting to follow J. Ulrych’s thoughts that the T i>0,5pfu requirement in the definition of kaersutite sets an arbitrary line and “separates genetically uniform hornblendes even within one locality into kaersutite and ferro-pargasite. Hence, the adoption of a limit characterized by 0.3 pfu Ti seems to be at some localities more suitable”

Pyroxene (augite) is very often mineral at this locality. It forms up to circa 8 cm long crystals, often grown into polycrystalline aggregates.

Partly altered/transformed? olivine (forsterite) is characteristic mineral for the locality. It occurs as up to 3 cm large well-developed crystals which are often grown into the augite crystals. Other macroscopic minerals at the locality are: phlogopite , hyalite, phillipsite and aragonite.”

Similar amphibole from Vlčí Hora has also been analaysed as titanian pargasite (tschermakite?) by Pavel Kartashov:

K0.34(Ca1.30Na0.69)1.99(Mg3.45Fe3+0.64Al0.57Ti0.34)5.00[(Si5.51Al2.49)8.00O22 ]O0.52.

Literature:

J. ULRYCH1, J. K. NOVÁK1, F. E. LLOYD2, K. BALOGH3, GYÖRGY BUDA (2002): ROCK-FORMING MINERALS OF ALKALINE VOLCANIC SERIES ASSOCIATED WITH THE CHEB-DOMAŽLICE GRABEN, WEST BOHEMIA
Acta Mineralogica-Petrographica, Vol. 43, pp. 1-18

Z. Jirák ; F. Pechar; S. Vratislav(1986): Distribution of Cations and the Proton Location in Kaersutite.
Crystal Research and Technology 21 (12), pg. 1517-1519

Jaromír Ulrych (1986): Oxykaersutite from the Vlčí hora Hill near Černošín, West Bohemia

Kaersutite
Germany
Rhineland-Palatinate , Eifel Mts , Andernach , Kruft , Korretsberg Mt.


Kaersutitic amphibole, 10mm specimen	© C.H.M.-Schäfer

The Eifel area lies in Western Germany, near the borders to Belgium and Luxembourg. This region is one of the most interesting areas in Europe for collectors of microcrystals. This is due to relatively recent tectonic events (the last 430.000 years), leading both to rifting and volcanic activity. A large number of vulcanoes are in the area, with the Laacher See(13000 years old) as the youngest. An annual landlift of 1-2mm shows that the area may still be active.

Titanian amphiboles can be found as phenocrysts in the volcanic rocks in the Eifel lavas. Although various pyroxenes are more common as phenocrysts also the amphiboles can be found as well formed crystals embedded in the lava rocks.

The titanian amphiboles from the Eifel area can be either titanian pargasite, kaersutite or titanian magnesiohastingsite.

Litterature:

Cliff S. J. Shawa and Jimena Eyzaguirre (2000) Origin of megacrysts in the mafic alkaline lavas of the West Eifel volcanic field, Germany, Lithos, Volume 50, Issues 1-3

57Fe Mössbauer study of volcanic hornblende (1975) Chemical Physics Letters, Volume 30, Issue 3. Pages 403-405

M. Darby Dyar, Stephen J. Mackwell, Ann V. McGuire, Laura R. Cross, J.David Robertson (1993): Crystal chemistry of Fe3+ and H+ in mantle kaersutite: Implications for mantle metasomatism, American Mineralogist, Volume 78, pages 968-979

Deer, Howie, Zussman, (1997): Rock forming minerals, Double-chain silicates

Leake, (1968): A Cataloge of analysed calciferous and subcalciferous amphiboles...
(cataloge of recalculated and renamed amphibole analyses that have been published post 1890)

Kaersutite
Germany
Rhineland-Palatinate , Eifel Mts, Mendig, Bell, Rothenberg Mt. (Rothenberg quarry)


Kaersutitic amphibole 35mm FOV	© C.H.M.-Schäfer

See text above.

Kaersutite
Greenland
Kitaa (West Greenland) Province, Uummannaq (Umanak) Firth , Qaersut (Kaersut)


Kaersutite 50mm FOV	© C.H.M.-Schäfer

Qaersut is a small, remote village on the east coast of Greenland, and the type locality of kaersutite. The Qaersut amphibole was first described as a new mineral by Lorenzen (1884) on the account of its high Ti content. It took some time before kaersutite was acknowledged as a separate species as it’s optical properties was inseparable from other amphiboles, and chemistry was, at the time, one of many characteristics defining a mineral species.

Kaersutite was found in a nearly horizontal, 50m thick peridotite (picrite) sill penetrating Devonian sandstone. The peridotite sill is not homogenous, having some layers enriched in augite and a 1-2m wide doleritic band in the centre.
“In addition, there are numerous segregations of kaersutite-bearing pegmatite comprising a horizontal sheet 35-40cm thick traversing the upper portion of the sill” (Benson).

Kaersuitte is found as several cm long elongated crystals embedded in feldspar. Published analytical data from this rather unusual occurance shows a Ti content between 0,9 and 1,2 afu or +/- 10%wt TiO2.

Litterature:

Deer, Howie, Zussman, (1997): Rock forming minerals, Double-chain silicates
Benson, (1939): Mineralogical notes from the University of Otago, N.Z. No 3: Kaersutite and other brown amphiboles in the Cainozoic igneous rocks of the Dunedin district.

Kaersutite
Italy
Trentino-Alto Adige , Trento Province , Fiemme Valley , Predazzo


Kaersutitic amphibole 30mm crystal	© Simone Citon


Kaersutitic amphibole 12mm crystal	© G.Fraccaro

Kaersutitic amphibole can be found as well developed crystals in a calc-alkali suite of shallow intrusions. I have found no analytical data and will need some help for this location.

Litterature:

Demartin, F., Campostrini, I., Grisotto, M., Grisotto, L. (2006): I Cancozzoli. Una classica località presso Predazzo, Val di Fiemme, Trento. Rivista Mineralogica Italiana, 30, 166-177.

Kaersutite
Italy
Sicily, Catania Province, Etna Volcanic Complex, Mt Etna


Kaersutitic amphibole 7mm crystal	© Enrico Bonacina

Mt Etna is the largest active volcano in Europe today. The volcano reaches and altitude of 3315m and it's lavas covers 1260 km². The 600.000 year volcanic history is divided in four main evaluation stages:

1st stage: (580 to 225 ka) tholeiitic basalts which today can be found in outcrops out as pillow-lavas, hyaloclastites
and sills along the Ionian Sea coast north of Catania.

2nd stage: (220 to 96 ka) The lava composition changes from tholeiitic to Na-alkaline (Branca et al. 2004). A number of central volcanoes (Ancient Alkaline Centres or Timpe Volcanoes) were constructed over a time span of about 100 ka (172 to 96 ka), and their remnants mainly crop out along the present-day margin of Etna. It is in these ancient lavas kaersutitic amphibole can be found as well formed crystals. Published data by Rruff.org of an amphibole crystal gives a kaersutite composition w/ Ti= 0,64afu.

3rd stage: (80-60ka) A series of effusive and explosive eruptions built a series of successive cones Successively, the so-called Trifoglietto unit

4th stage: (60ka-present): The building of the current stratovolacano.

During the various eruptive stages, the composition of the amphiboles have changed, from kaersutitic amphiboles in the ancient stage 2, via pargasites to magnesiohastingsite in the latest 2001/2002 eruption. Correct identification of an Etna amphibole should consequently be based on a reliable analysis of the crystal.

Litterature:
Angelo Peccerillo (2005): Plio-Quaternary Volcanism in Italy, Springer Verlag, Chapter 8 Sicily.

M. Viccaro, C. Ferlito and R.Cristofolini (2007): Amphibole crystallization in the Etnean feeding system: mineral chemistry and trace element partitioning between Mg-hastingsite and alkali basaltic melt (2007)
Eur. J. Mineral. 19, 499–511

Kaersutite
New Zealand
South Island, Otago, Kakanui

Kaersutite constitutes an important part of the ultramafic inclusions in the mineral breccia at Kakanui. It is associated with garnet, clinopyroxene and magnetite. The mineral breccia is a mantle-sourced diatreme with associated marine reworked volcaniclastics. Mantle xenoliths include lherzolite and garnet pyroxenites occurring with megacrysts of garnet, clinopyroxene, kaersutite, and feldspar.

Kaersutite usually occurs as irregular crystals enclosed in the matrix. Occationally, rounded, simingly “polished” crystals up to 5 cm in diameter and 15 cm length can be found. The “polished surface is probably due to friction in the mineral breccia.

Analytical data suggest that the Ti content in the kaersutite lies between 4,98 and 5,87 wt% TiO₂

Litterature:
Kenzo Yagi, Yu Hariya, Kosuke Onuma and Noriko Fukushima (1975): Stability relations of kaersutite,
Jour. Fac. Sci. Hokkaido Univ., Ser IV, Vol 16, no 4

R. Clearland Wallace (1977): Anorthoclase-calcite rodding within a kaersutite xenocryst from the Kakanui Mineral Breccia. New Zealand
American Mineralogist, Volume 62

Kaersutite
USA
Arizona, Otago, Mohave Co., Minnesota District,Hoover Dam vicinity - 8 miles South


Kaersutite, 8x4cm spec.	© Jorge M. Alves

Kaersutite can be found as up to 10cm large megacrysts in camponite dikes. The best known dyke, and also the source of most of the Hoover (Boulder) Dam kaersutites come from a road cut some 8 miles south of the dam itself. The dyke is 4ft wide and the near vertical orientation give a 12ft exposure in the road cut. Kaersutite can also be found in other camptonite dikes in the area.

The kaersutite megacrysts gets larger towards the centre of the dyke. It is believed that rapid cooling towards the walls of the dyke trapped the volatile elements within the dyke, thus allowing larger kaersutites to form towards the centre of the dyke. The kaersutite seems to have grown rather rapidly ( Campell and Schenk suggests 25 days)
Published data seems to indicate a Ti content ranging from 5,49-5,78%wt TiO2

Litterature:
Ian Campell and Edward T. Schenk (1950): Camptonite dikes near Boulder Dam, Arizona.(1950), American mineralogist volume 35.
Michael O.Garcia, David W. Muenow, Norman W. K. Liu (1980): Volatiles in Ti-rich amphibole megacrysts, southwest USA, American Mineralogist, Volume 65

Olav Revheim June 2011

Click here to view Best Minerals K , and here for Best Minerals A to Z and here for Fast Navigation for finished Best Minerals articles.]]> Olav Revheim Best Minerals K Tue, 24 May 2011 07:24:26 +0000 http://www.mindat.org/forum.php?read,77,165266,165266#msg-165266 Kyanite (25 replies) http://www.mindat.org/forum.php?read,77,165266,165266#msg-165266 Best Minerals K and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.

Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities? After each set of pictures there should be some descriptive text. If none appears it means that we need someone to tell us about the specimens from that locality and something about the geology of the occurrence.

Kyanite Al₂SiO₅ Triclinic


Kyanite & Quartz,17.2cm tall	© Rob Lavinsky

Galiléia, Doce valley, Minas Gerais
Kyanite is an important metamorphic rock forming mineral and is important in determining the metamorphic conditions that the rock experienced. Kyanite is formed under high pressure, relatively low temperature ( 2+ kbars pressure and temperatures in the 350-600C range) regional metamorphic conditions where the original rock was fairly high in aluminum content (shales). The rocks will be gneisses, schists, and pegmatites and quartz veins included in these rock types. Kyanite can also survive some weathering and be found in detrital material (sands) and some sedimentary rocks.

Color: Blue, white, rarely green, gray, yellow, pink, black, commonly can be zoned with central blue color and a clear outside zone.

One of the minerals distinctive characteristics is the large difference in hardness which depends upon the crystallographic direction. Hardness = 5.5 parallel to [001] (c-axis), 7 parallel to [100] (a-axis).

Crystals are bladed and tabular on {100}, elongated parallel to [001], to 0.5 m; typically bent or twisted. Twinning is common. From metamorphic rocks, the habit is short to long prismatic along c-axis and tabular on {100} generally less than 10 cm. In pegmatites and quartz lenses the kyanite crystal habit is long prismatic.

Kyanite is polymorphous with sillimannite and andalusite. It is commonly pseudomorphed to andalusite.

While kyanite is a relatively common mineral, good crystals are fairly rare. The best crystals have been found in pegmatites as well as quartz veins. Recently, Brazil has been a producer of fine specimens. Small amounts of the crystals are of facet grade, but the species is only marketable to collectors of rare stones.

Kyanite
Antarctica
Eastern Antarctica, Enderby Land, Prince Olav Coast (Prince Ulaf Coast)


Kyanite 6.5 cm wide	© Pavel M. Kartashov

Kyanite
Australia
Northern Territory, Harts Ranges (Hartz Ranges), Huckitta Well


Kyanite 9cm tall	© Patrick Gundersen


Kyanite 7.5cm tall	© Patrick Gundersen

Kyanite crystals from the Harts Range have reached 30 cm.

Kyanite
Austria
Styria, Ennstaler Alpen Mts, Admont, Klosterkogel Mt., Gablergraben


Kyanite in schist polished slab 10cm	© Franz Bernhard


Kyanite, Polished slab 7cm wide	© Franz Bernhard

Kyanite
Brazil
Bahia


Kyanite 4.1cm tall	© Michael c. Roarke


Kyanite 7.9cm tall	© Rob Lavinsky


Kyanite 26.8 cm	© Rob Lavinsky


Kyanite in Quartz ~20cm tall	© Philip


Kyanite & Quartz 16cm wide	©


Kyanite 6.1cm	©

Kyanite
Brazil
Goias


Kyanite 2.7cm	© Lavinsky

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Kyanite 3.8cm	© Weinrich Minerals

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Kyanite 2.4cm tall	© Rob Lavinsky

We need better localities for the specimens labeled just Minas Gerais, Goias and Bahia. Some of the images we show for these localities are probably not correct. Luiz, can you help us out with these?

Kyanite
Brazil
Minas Gerais


Kyanite & Quartz 11cm	© Rob Lavinsky


Kyanite xl 5.7cm wide, gem=1.42ct	©

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Kyanite Quartz 4.9cm wide	© Rob Lavinsky

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Kyanite 4.1cm wide	© Rob Lavinsky


Kyanite 7.5cm wide	© Antonio Borrelli


Kyanite 7cm wide	© Marcelo O. Olsina

Kyanite
Brazil
Minas Gerais, Doce valley, Galiléia


Kyanite & Quartz 17.6cm tall	© Rob Lavinsky

Kyanite
Brazil
Minas Gerais, Jequitinhonha valley, Coronel Murta, Barra de Salinas, Barra de Salinas district

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Kyanite 10.5cm	©

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Kyanite & Quartz 4.6cm tall	©

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Kyanite & Quartz 9.7cm	©


Kyanite & Quartz 19cm wide	© Rob Lavinsky

Kyanite
Kenya
Eastern Province, Makueni District, Umba Valley Region, Sultan Hamud


Kyanite 18cm long	© 2003 John H. Betts


Kyanite 7.4 cm	© Rob Lavinsky

Kyanite
Norway
Finnmark, Hasvik, Sørøya, Båtberga


Kyanite & Quartz 7cm wide	© A. Michalsen


Kyanite in Quartz 6cm tall	© A. Michalsen

Kyanite
Russia
Urals Region, Southern Urals, Chelyabinsk Oblast', Borisovskie Sopki


Kyanite in mica schist 6.4cm wide	© Igor Savin


Kyanite in mica schist 5.7cm wide	© Igor Savin

This deposit (Borisovskie Sopki) was found at the end of 19th century. Now it is developed only by mineral collectors and consists of several open pits. The largest crystals from this deposit were 20 cm long. I saw crystals with dimensions of about 15 x 3 x 1 cm. Kyanite crystals have inclusions of quartz, mica, rutile, and tourmaline. Gem material is rare.
[Igor Savin 2010]

Kyanite
Russia
Northern Region, Murmanskaja Oblast', Kola Peninsula, Keivy Mountains, Pestsovye Keivy

Kyanite found in quartz lenses with crystals reaching 100cm. Also from this locality are Kyanite pseudomorphs "sausages" after chiastolite crystals 25 to 20 cm long. Unfortunately any real unreplaced andalusite absent on the locality.

We need to normalize this deposit with a valid Mindat locality string. Pavel will upload an image

Kyanite
Switzerland
Ticino (Tessin), Leventina, Central St Gotthard Massif


Kyanite in mica 7.8cm tall	© Rob Lavinsky


Kyanite & Staurolite ~45cm wide	© J.N. Wingard

The locality for the large specimen pictured above may be in error and it is thought it is actually from Sponda Alp - Pizzo Forno, Chironico Valley, Leventina, Ticino (Tessin), Switzerland. If this is confirmed we will be moving the image.

Kyanite
Tanzania
Arusha Region, Loliondo, Nani


Kyanite twin 3.5cm wide	© MAWINGU GEMS


Kyanite 5cm tall	© Rob Lavinsky

Kyanite
USA
Connecticut, Fairfield Co., Redding


Kyanite & Quartz ~8cm wide	© Michael Otto

Kyanite
USA
Connecticut, Litchfield Co., Litchfield


Kyanite 19cm tall	© Rob Lavinsky

Kyanite
USA
North Carolina, Buncombe Co., Pisgah National Forest, Meeper Mine


Kyanite & feldspar ~20cm wide	©


Kyanite & feldspar ~14cm wide	©

I'd have to say that Meeper mine probably is the best Kyanite locality in the USA bar none, some of the crystals that came out of there are on the order of 16 inches long, 3 to 4 inches wide and 1 inch thick.
[Everett Harrington 2009]

Kyanite
USA
North Carolina, Buncombe Co., Thomas Mine (Balsam Gap kyanite location; Parkway kyanite location)


1.3cm terminated Kyanite & Quartz	© 2002, Keith Wood

I did my MS thesis in geology on the Thomas mine, otherwise known as the Parkway or Balsam Gap sites. The main issue in my thesis was whether the Thomas occurrence was of igneous or metamorphic origin. The answer turned out to be igneous, and the reasons for this were a good deal more complicated than need be elaborated here.

As part of my study I also examined the Meeper occurrence and the Swan prospect, which both also contain igneous kyanite within pegmatites. These sites are all within 1.5 miles of each other. Of these the best was the Thomas mine, named for Luther Thomas, a well-known collector in the NC mountains. Kyanite there reached lengths up to 29 inches by 3.5 inches by 1 inch - that was the single largest crystal Luther ever collected there, and I have a third of it on one ninety pound specimen in my collection. Kyanite from the Thomas mine was found in the typical white to dark blue colors, with common center zoning of the blue parts. This blue is due to ferric iron. However, many crystals, especially those in the outer zone of the pegmatite, had a rich teal coloration that XRF work showed to be related to chromium as a chromophore. This color could also be found at the Meeper mine. I have not been able to reproduce this particular color well in digital photos. This chromium coloration typically was not zoned within the crystal, whereas the ferric iron blue could be zoned in a chromium colored specimen, yielding some crystals with a solid teal coloration and a deep blue streak in the middle. Specimens with this coloration and good clarity were considered highly desirable.

Another distinctive of the Thomas mine was the very high quality of the crystallization, with many less common crystal forms well represented, including several terminal forms rarely observed elsewhere. I have two well-terminated crystals in my collection, but the best terminated specimen I saw from there was a piece collected by one of the Ledford brothers in NC, a deep blue crystal 2x1x.3 inches with a complete termination. Numerous specimens of gem quality were recovered from the Thomas mine, and several gemstones were cut from this material. The best specimens were probably those collected by Luther Thomas and his son(s) in the 80s. Luther has since passed away and I assume that most of his collection went to his son Icket.

The Thomas mine probably deserves to be considered the best kyanite location in North America. It bests the Meeper mine in having crystals that were less altered on the outside, often being very well exposed in the rock. Much of the Kyanite from the Meeper mine has a sericite/muscovite coating on the outside that causes the crystals to adhere to the matrix too well, resulting in cleaving of the crystals.

None of these "mines" were worked commercially to anyone's knowledge, however the discovery histories and first workings are lost in obscurity. The portion of the Thomas mine Luther worked was a second pegmatite he and his son discovered down hill from an original pit of unknown origin. The original pegmatite may have been discovered during construction of the Blue Ridge Parkway, but no specimens are known to have survived. It is possible the kyanite may have been mined for use in ceramics as the waste piles of the original pit contained numerous small but very beautiful specimens that certainly would have been of mineralogical interest. It is unlikely such specimens would have been discarded had mineral collecting been the been the motive. The Meeper mine may have been discovered during mica prospecting in the area, as there are known mica-producing mines with a few miles and the entire area is in prospective rocks for mica mining. All three of the kyanite occurrences I am discussing fall within the Buncombe pegmatite district.
[Keith Wood 2010]

Kyanite
USA
North Carolina, Yancey Co., Blue Rock Asbestos Mine


Kyanite & Quartz 8cm wide	© 2009 M. Harrison

I have just spent some hours trying to fix the mess on the Brazilian kyanite localities; I have already made the corrections on Rob Lavinski's photos and sent complaints to everybody else that have uploaded photos with wrong localities; the most common mistakes were the following:

- Blue Kyanite on Quartz - there are only 2 localities in Brazil that have produced commercial quantities of high quality specimens: Barra do Salinas district, Coronel Murta, Minas Gerais (on the list of localities it is written as "Barra do Salinas district, Barra do Salinas, Coronel Murta, Jequitinhonha valley, Minas Gerais"; there is an un-necessary repetition of "Barra do Salinas"), and São José da Safira, Doce valley, Minas Gerais; I can make a distinction among them, on most cases, based on the following criteria:
- the best specimens from Barra do Salinas have a deeper blue color than the best specimens from São José da Safira; tha lateral faces of the prisms tend to be pure kyanite, whilst both the main prism faces as well as the lateral faces on the crystals from São José da Safira tend to show a variable amount of intergrowth with thin white muscovite; finally, Barra do Salinas produced intensively during the 1990's until about 2004/2005, when the production started to decline sharply, and it coincides with the start of intense production from São José da Safira; unfortunately on mid to low-quality specimens it is much harder to make a distinction
- there are no blue kyanites in quartz in Bahia state neither in Galileia, Araçuaí or Governador Valadares, in Minas Gerais
- I have recently found out that the bicolor kyanites (green with a central blue stripe) come from Vitória da Conquista, Bahia
- all black kyanites come from Ribeirão da Folha, near Capelinha, Minas Gerais; Araçuaí and Governador Valadares are wrong localities; I have not send complaint messages yet because I have to double check later today, in my office, if the locality is inside Capelinha or in Novo Cruzeiro county
- there is a locality in Goias state that produced thick prismatic kyanite crystals, showing intense blue color, inside a talc-schist matrix; unfortunately I still don't know the precise locality
- Brumado have produced pale blue kyanite crystals on magnesite matrix, but there were no photos of this material on the gallery; 2 photos of dark blue kyanites in quartz, listed as from there, are indeed from Barra do Salinas.
[Luiz Alberto Dias Menezes, Fo. 2012-[www.mindat.org]]

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]]> David Von Bargen Best Minerals K Tue, 07 Sep 2010 04:21:48 +0000 http://www.mindat.org/forum.php?read,77,143465,143465#msg-143465 Kernite (1 reply) http://www.mindat.org/forum.php?read,77,143465,143465#msg-143465 Best Minerals K and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.

Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?

Kernite
Na₂[B₄O₆(OH)₂] · 3H₂O Omonoclinic


1. Kernite, 12cm wide	©

Kernite occurs in crystals (are you ready for this?) in crystals up to 3.5 meters in length although it is not usually a mineral you would want to put in your collection because under normal atmospheric conditions it will eventually end up, after a few years, as a pile of white powder in your specimen drawers unless you seal it up in a bottle and keep it in a cool dry place. It was discovered in 1925 during a drilling program by the United States Borax Company in the Mojave Desert. This locality originally known as the Kramer District is today know as Boron, California, the name of the little town that developed after mining of the deposit began. Usually new minerals are found only in small quantities and here was one that occurred in a masses of large intergrown crystals in a deposit 30 meters thick.¹ The mineral was known as rasorite till it was given the name Kernite by Schaller in 1927. It is found in the lower part of the borate ore body below the thick beds of Borax and apparently is the result of a low grade metamorphic process where the Borax looses some water and forms Kernite. In 1948 a second locality for Kernite was found at Tincalayu, Argentina. The crystals though not nearly as large and the deposit not so extensive, it is similar to the Kernite found at Boron. Even today, there are less than a half dozen known localities. In some circles that might qualify it as a rare mineral, except that where it is found, there are thousands of tons of it. The borate deposit at Kirka in Turkey also has a substantial content of the sodium borates of Borax and Kernite.²
1. Palache, C., H. Berman, and C. Frondell (1951) Dana's System of Mineralogy, (7th edition), v.II, 335-337. 2. Cahit Helvaci & Ricardo N. Alonso. Borate Deposits of Turkey & Argentina: A Summary and Geological Comparison. Turkish Journal of Earth Sciences, Vol.9, pp1-27.
[Rock Currier 2009]

Kernite
USA
California, Kern Co., Kramer District, Boron, U.S. Borax Open Pit Mine


2.Kernite, 14.5cm wide	©


3.Kernite,11cm wide	© 2008 Jesse Crawford


4.Kernite, 4cm across	© Peter Haas

More than 30 crystal forms of Kernite are known¹ but I wonder where in the world they found the crystals to measure. The only well developed crystals of Kernite I have seen have been from the giant dissolving tanks in the borate refinery at Boron and I suspect that the Kernite crystal pictured #4 above may be one of these. Periodically these big million gallon + tanks needs to be opened for clean out and maintenance. They break down the side of these big round concrete tanks so they can drive a bulldozer inside to clean things out and Kernite and Tincalconite crystals are found growing on the blades and walls of the tank. Perhaps when Palache, Berman and Frondel studied and described Kernite they had at their disposal crystals from the deposit that I have never seen, but let me assure you that if these crystals still exist (they may have hydrated to Tincalconite and fallen apart) they are rare creatures indeed. Given the size of the Kernite deposit at Boron, there are undoubtedly places where if you carefully washed the mud off the Kernite, crystal faces might indeed be found. But neither I or Jim Minette who was mine manager (both mineral collecting fiends) had any of these in our collections. As far as I know all the Kernite found at Boron is found at the bottom of the deposit where under the pressure of overlying rocks and perhaps modest heat, it lost some of its water and was altered to big intergrown lath like masses of Kernite. Kernite has sometimes been processed as ore, but it is not easy to process because of its perfect cleavage it does not break up nicely in small chunks, but forms nasty masses of splinters that have a habit of screwing up processing machinery. Some processing has been done by placing it in large piles and sprinkling it periodically with water. This allows the natural process of hydration ultimately into Tincalconite and the solution draining from the pile is rich in sodium borate and this can be readily processed into various borate compounds. At Boron, the company has built a nice little museum/visitor center overlooking the large open pit mine, and they periodically dump a truck load or two of ore from the deposit for visitors to pick through and haul off. Many times it consists of Kernite which when it is fresh looks great because it is fairly transparent to translucent and makes good specimens. See pictures 1,2 & 3 above. Tons of these specimens have been hauled away from the mine only to later gradually morph into mounds of white powder.

1. Palache, C., H. Berman, and C. Frondell (1951) Dana's System of Mineralogy, (7th edition), v.II, 335-337.
[Rock Currier 2009]

Click here to view Best Minerals K and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.]]> Rock Currier Best Minerals K Thu, 02 Jul 2009 10:35:20 +0000 http://www.mindat.org/forum.php?read,77,143453,143453#msg-143453 Kurnakovite (1 reply) http://www.mindat.org/forum.php?read,77,143453,143453#msg-143453 Best Minerals K and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.

Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?

Kurnakovite
Mg(H₄B₃O₇)(OH) · 5H₂O triclinic


1.Kurnakovite & Ulexite,~11cm wide	©

Kurnakovite is a relatively rare borate mineral and is found at fewer than 10 localities thus far. It is dimoprhous with Inderite. Crystals of more than 30 cm have been found, and crystal clusters can exceed 50 cm. These well crystallized specimens are exclusively from the borate deposit at Boron, California and the specimens found at other localities are poor second cousins. The mineral was first described by the Russians from the Inder deposit in Kazakhstan.
[Rock Currier 2009]

Kurnakovite
Kazakhstan
Atyrau Oblysy (Atyrau Oblast'), Atyrau (Gur'yev), Inder B deposit and salt dome


2.Kurnakovite, 2.8cm wide	© Peter Kohorst

From the single picture we have of a specimen from Kazakhstan, the material looks to be earthy and massive. We need someone to tell us about the borates from the Inder locality in Kazakhstan.

Kurnakovite
USA
California, Kern Co., Kramer District, Boron, U.S. Borax Open Pit Mine


3.Kurnakovite, ~7cm diameter	©


4.Kurnakovite crystals.	© Caltech


5.Kurnakovite ~3cm tall	©


6.Kurnakovite ~12 cm tall	© Rob Lavinsky

The Kurnakovite crystals from the borate deposit at Boron, were almost all found during the early days of the open pit mine when they switched over from underground to open cast. They were found in a fault zone near the west end of the deposit. Many of the Kurnakovite crystals were found growing in the distinctively colored blue/gray/tan mud of the deposit and almost always associated with little intergrown fibrous knobs of Ulexite that are commonly stained to a greater or lesser extent by the mud from the deposit. When these were encountered hundreds of crystals were collected. Even ten years after the fact I was able to buy more than 100 crystals in a bag from a miner that had never been cleaned. Sometimes the crystals of Kurnakovite were more than a foot in diameter and clusters of these crystals of more than a half meter are known. The crystals for the most part are blocky with some few being tabular. Very rarely they were associated with Inderite crystals. Some pocket material with free standing crystals were found, but these pockets were never very big. Since the original discovery, in the 50s, no more specimens of Kurnakovite have been made. When specimens of Kurnakovite are transported from the dry clean desert air of the Boron area, down into the polluted air of Los Angels, it is typical for the specimen to develop a white coating starting on the edges of the crystals and then white spots appear on the crystal faces and finally a thin white coating will develop to coat the entire specimen like seen in picture #3. The crystals that remain in the clean dry air of Boron are rarely affected with this problem. It is commonly ascribed to a dehydration process, but I believe that in the polluted air of big cities that the Kurnakovite is reacting with some of the containments in the air. This coating can be largely removed by soaking the specimen briefly in water. Other than this, Kurnakovite and Inderite are stable and do not fall apart like the sodium borate minerals found at Boron. These large crystals of Kurnakovite are quite heat sensitive and if you put in in water that is warmer or colder than the crystal, you will crack it. Take it from one who has done just that. Probably fewer than 1000 specimens of all kinds were collected.
[Rock Currier 2009]

Click here to view Best Minerals K and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.]]> Rock Currier Best Minerals K Wed, 01 Jul 2009 03:56:38 +0000 http://www.mindat.org/forum.php?read,77,139665,139665#msg-139665 Kamotoite-(Y) (2 replies) http://www.mindat.org/forum.php?read,77,139665,139665#msg-139665 Best Minerals K and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.

Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?

Kamotoite-(Y)
Y₂(UO₂)₄[O₄|(CO₃)3] · 14H2O Monoclinic


Kamotoite-(Y), Kamoto East Open cut, Kolwezi, Katanga DR Congo 16.4cm wide	© Paul De Bondt

Kamotoite-(Y)
Congo, Democratic Republic of
Katanga (Shaba), Katanga Copper Crescent, Western area, Kolwezi, Kamoto, Kamoto East Open cut


Kamotoite-(Y) FOV 5mm	© Thomas Witzke


Kamotoite-(Y) & others 5.8cm wide	© Rob Lavinsky

The pictured specimen is the best specimen known and comes from the personal collection of J.M. Pendeville, who discovered the pocket and is now in my collection. The second best specimen is in the Sorbonne, Paris, collection. The third best is also in my personal collection. The specie is not rare at the deposit but good crystallized specimens are very rare and only less than 5 are top grade. Most specimens are crystalline masses or coatings. The mineral sit on unaltered massive Uraninite and is VERY radioactive. The Uraninite from Shinkolobwe is around 656 milion years old ( Dr. Michel Deliens ) The Uraninite from Kamoto must be younger because for the same quantity, the radiation is much higher.

Kamotoite was discovered in the early 1980’s by the late Jean-Marie Pendeville in the Kamoto East open cut, situated near the city of Kolwezi, Western area of the Katanga Copper Belt in the Democratic Republic of the Congo. The formal description was done in 1986 by M. Deliens et P. Piret. Kamotoite is a hydrated Carbonate of Uranyl and Rare Earths. The REE are in declining order of importance, Y, Nd, Gd, Sm and Dy. It is the most important mineral that was found in a Uranium-bearing pocket associated with Shabaite-(Nd), Astrocyanite-(Ce), Schuilingite-(Nd) and Uranophane. A little Curite is also present. The mineral has a very attractive lemon to golden yellow colour and forms rarely radiated structures.
The crystals are monoclinic and are terminated in a point forming an angle of 35 °. As of 2009 only 5 occurrences are known and Kamoto East is the most important.
[Paul De Bondt 2009]

Perhaps we should include a description of Kamotoite-(Y) from other localities here, but we need someone to tell us about them and to upload pictures of them. I have a feeling that compared to the specimen pictured above, they would all be at least two orders of magnitude less quality, probably barely yellow stains on rock. Does anyone have information to the contrary? Actually I am pretty sure that some decent micro crystals have been found at some of these other localities, but am trying to goad some of the people who specialize in minerals from those areas to step up and help us make this a better article.

Click here to view Best Minerals K and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.]]> Rock Currier Best Minerals K Thu, 04 Jun 2009 08:30:44 +0000 http://www.mindat.org/forum.php?read,77,129403,129403#msg-129403 Best K Minerals - Welcome (1 reply) http://www.mindat.org/forum.php?read,77,129403,129403#msg-129403
Ideally what we want to know about each significant mineral from each locality is:

1. What is the largest crystal of the mineral that the locality has produced?
2. What do the best specimens from this locality look like and where can one be seen?
3. Does the locality produce a variety of different kinds of specimens of this species, and what do the best of each type look like and how many of them were found etc.
4. What are the associated minerals found with this species and what is its geological setting?
5. How abundant are these specimens and when were they found? A type locality? In other words, how rare are they.
6. How do they compare to other specimens of the same mineral from other localities?
7. How much is it worth. This should probably be optional, but in cases where specimens are worth thousands of dollars we should probably say something of the value of these things.
8. What kind of care and feeding do these specimens require? Are they delicate, radioactive, unstable, color changeable etc.?
9. Are the specimens commonly faked, and if so, how to tell if they are?
10. Are there any interesting stories relating to the collecting of these specimens or their discovery as a new mineral?

Of course this is in reality impractical, but if we keep these questions in mind, we will do a lot better job when writing about them.]]> Rock Currier Best Minerals K Thu, 28 May 2009 13:05:02 +0000