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Pargasite series

Posted by Olav Revheim  
Pargasite series
June 15, 2011 08:37PM
    
First Draft




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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 pargasite 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:

Chloro-potassicpargasite
K Ca2(Mg4Al)(Si6Al2)O22Cl2

Ferropargasite
NaCa2(Fe4Al)(Si6Al2)O22OH2

Fluoropargasite
NaCa2(Mg4Al)(Si6Al2)O22F2

Fluoro-Potassic-pargasite
KCa2(Mg4Al)(Si6Al2)O22F2

Pargasite
NaCa2(Mg4Al)(Si6Al2)O22OH2

Potassicpargasite
KCa2(Mg4Al)(Si6Al2)O22OH2

Potassic-ferropargasite
KCa2(Fe4Al)(Si6Al2)O22OH2

Cl-analogue of Ferropargasite
NaCa2(Fe4Al)(Si6Al2)O22Cl2


Pargasite 12mm crystal. Luc Yen, Vietnam © Michael C. Roarke



The pargasite-series minerals belong to the calcio-amphibole subgroup, and is characterized by two Al atoms in the D position, a single valence atom in the A position and an Al atom in addition to 4 Mg or Fe in the C position. The pargasite molecule are quite stable, and pargasite-series minerals can consequently be found in a wide range of environments including amphibolites, skarns/ calc-silicate rocks and eruptive rocks. Some of the more sophisticated minerals in the series, such as fluoro- and chloro- pargasites that are known from only a handful localities.

The pargasite-series is of intermediate composition compared to the other calcio-amphiboles, and solid solution series exists towards the hornblende-series, the edenite-series, the tschermakite-series,the hastingsite series, the kaersutite series and the sanadagaite series. Often more than one amphibole is present at the given location, and it may also be difficult to accurately identify the amphibole species. In many cases the litterature references states something like "amphibole of tschermakitic or pargasitic composition".

The largest, well formed crystals of pargasite are known from calc-silicate rocks and marbles at Pargas, Finland as well as New York,USA, whereas the most attractive specimens will be the intense green, sometimes gemmy pargasite from the ruby bearing marbles of Pakistan, Burma and Vietnam. Particularily interesting are the combo specimens from Vietnam with grass green pargasite and red spinel. Also some of pargasites in lava from the Central European locations can be quite attractive for an amphibole.

The green Asian pargasites are amongst the most attractive amphibole specimens, and retail prices into 4 digits (USD) can be achieved for the biggest and best crystals.


Pargasite
Burma (Myanmar)
Mandalay Division, Sagaing District, Mogok, Pein Pyit (Painpyit)

Pargasite FOV 8mm©


The identification of this mineral has been confirmed by X-ray diffraction and chemical analysis (rruff.info)

The Pyant Gyi mine was originally opened to extract pinkish red spinels and pink scapolite from alluvial sediments. Later the mining operations extended into solid rock and today several small mines. High quality specimens of the rare mineral johachidolite has been found in an alkali-pegmatite in one of the mines together with other attractive mineral specimens . As a result, specimen mining both from the pegmatites and the marble/skarn has become interesting, and this pargasite specimen probably come from the marble zone.

Literature:

Adolf Peretti (1), Francesca Peretti (1), Ngwe Lin Tun (1), Detlef Günther (2), Kathrin Hametner (2), Willy Bieri (3), Eric Reusser (4), Milen Kadiyski (5), Thomas Armbruster (5) (2007): GEM QUALITY JOHACHIDOLITE: OCCURRENCE, CHEMICAL COMPOSTION AND CRYSTAL STRUCTURE, Gemresearch Swisslab, Contributions to gemology No 5.


Pargasite
Burma (Myanmar)
Mandalay Division, Sagaing District, Mogok,

Pargasite 1,8cm crystal© Rob Lavinsky


The pargasite appears to be found in the same geological environment as the rubies and other gems. The Mogok tract is predominantly a marble belt formed from Proterozoic sediments (>750 MYa) metamorphosed by collision with a Gondwana fragment (Burma Block) in Cretaceous time (~150 MYa) and later with the Indian block in Eocene time (~50 MYa), and with metamorphism to ~20 Ma and intrusions to ~15 Ma.

Many of the gem and collector minerals are formed in the marble itself during metamorphosis, or by metasomatic and pneumalytic processes in the contact zone between the marble and the surrounding rock. The marble is in contact with a wide range of igneous rocks, both granitic, mafic and alkali rocks of various ages and compositions. This gives an extensive mineral suite, of which pargasite is one.

Pargasite is the most common of the amphibole group minerals found in Mogok, and can be found as well formed, sometimes gemmy, light green crystals several minimum 6 cm long. The pictured specimen is deeper green than other pargasites from Mogok.

Literature:

George E. Harlow, Ayla Pamukcu, Saw Naung U, U Kyaw Thu: Mineral assemblages and the origin of ruby in the Mogok Stone Tract, Myanmar.


Pargasite
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) amphibole 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 (pargasite and kaersutite) is found in more than 70% of the more than 1000 alkaline dykes radially arranged to the main volcanic centre of the České Středohoří Mts. 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 apfu Ti.

The amphibole crystals found at the majority of the locations listed in the kaersutite-series article, see kaersutite series article, are borderline pargasite/kaersutite. This means that both kaersutites and pargasites may be found at these localities, and only an anlysis of the individual crystal will determin the species. The IMA amphibole subcommittee recommends the term "kaersutittic amphibole" in these cases.

The Czech locations are amongst the most profilic of these locations and are therefore included in the pargasite article as well as the kaersutite article to highlight that "kaersutites" from a kaersutite location without the support of a individual crystal analysis may equally well be a pargasite.

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


Potassicpargasite
Finland
Länsi-Suomen Lääni, Turku-Pori, Pargas (Parainen), Simonby

Potassicpargasite © 2008, JGW


The pictured specimen is confirmed by EDS.

There are two abondoned limestone quarries near Simonby, and the pargasite is from the quarry east of the village. This quarry was rich in micas, pargasite, pyroxene and scapolite, frequently occuring in nice crystals. This quarry was already abandoned in 1867.

The holotype of potassicpargasite is located in the collections of the Canadian Musuem of nature, where a systematic systematic electron-microprobe investigation of amphiboles revealed a potassium dominant pargasite. The specimen had been labeled "Hornblende, Franklin" when entered into the collection, but the lack of Mn and Zn in both the potassicpargasite and the calcite host indicated that the given location was incorrect. Further investigations indicates that Parainen (Pargas) probably is the correct location.

It should be noted that it is impossible to distinguish the various pargasite-series amphiboles from Pargas without a quantitative analysis for each crystal. It should also be noted that each crystals may be zoned, and each crystal may contain more than one mineral. Without such analysis, it is recommended that these specimens be labeled "Pargasite-series". It is difficult to estimate how common potassicpargasite is compared to pargasite, and an attempt to distinguish between the two in mode of occurance or maximum size makes little or no sense.

Literature:

Alphons Kuhlberg(1867): Die Insel Pargas (Åhlön), chemisch-geognostisch untersucht, Magisterwürde Abhandlung der Kaiserl. Universität zu Dorpat

George W. Robinson, Joel D. Grice, Roberta Gauli, Andre E. Lalonde (1997): Potassicpargasite, a new member of the amphibole group from Pargas, Turku-Pori, Finland, The Canadian Mineralogist, Vol. 35, pp. 1535-1540(1997)


Pargasite
Finland
Länsi-Suomen Lääni, Turku-Pori, Pargas (Parainen)

Pargasite 4cm specimen © B. Otter
Pargasite 6 cm specimen © Rob Lavinsky

Pargas ( Parainen) is one of the classic mineral locations in Europe. It has been known for large, well formed amphibole-group crystals from skarn and marble rocks since the time latin still was used as the lingua franca for scientific papers. The first written records of industrial explotation of the calcite marble at Pargas dates back to the 18th century.

The marbles themselves originate from a 1,9 billion sequence of sediments and supracrustal (formed on surface) volcanic rocks, which is later metamorphosed to predominantly gneisses, micaschists, amphibolites as well as marble layers and lenses. A characterisitc feature of the Pargas ( Parainen) geology is a 15 km long amphibolite ring structure. The marbles follow the inside of this ring as layers of variable thickness, in which intermediate layers of quartz/feldspar gneiss. The interesting minerals are formed in the contact between the sorrounding/intermediate rocks and the predominantly calcite marble.

Pargasite occurs with scapolite and pyroxen as well developed crystals embedded in coarse calcite. The more transparent the calcite gets, the larger and better developed are the pargasite crystals. Nordenskiold(1821) describes greenish black crystals up to 4x3 in, and smaller ( up to 1,5in) green crystals from several quarries in the area.

It is interesting to see how these earliest mineralogists struggled to distinguish between pargasite and hornblende with identical chemistry and crystal shape based on small differences in appearance (color and ease of cleavage), whereas we today struggle to distinguish amphiboles with identical appearance based on small differences in chemistry.

Literature:

Nils Nordenskiöld (1821): Mineralogische Beschreibung des Pargasits und Hornblende as Pargas, Journal für chemie und physik, 31ste Band

Ritva Karhunen (2004), Iniön ja Turun kartta-alueiden kallioperä (Berggrunden inom Iniö och Åbo kartblad), Suomen geologinen kartta ( Geological map of Finland), Geologian tutkimuskeskus (Geologiska forskningscentralen/ Geological Survey of Finland)


Pargasite
Finland
Länsi-Suomen Lääni, Turku-Pori, Pargas (Parainen), Ersby

Pargasite 7cm crystal © Knut Eldjarn
"Hornblende", probably pargasite. 4cm crystal ©

This was the best location for pargasite in the early 19th century. Although of very similar composition ( see V. Bondorf (1821), scientists at the time distinguished between green pargasite and greenish black "hornblende" (see [www.mindat.org]). Pargasite occured as well formed, doubly terminated crystals embedded in calcite.

Literature:

P.A v. Bonsdorf (1821):Försök att bestemma sammensetningen af de Mineralier, hvilka kristallisera i Amphibolens form. Kongl. vetenskaps academiens handlingar, Volum 9

Alphons Kuhlberg(1867): Die Insel Pargas (Åhlön), chemisch-geognostisch untersucht, Magisterwürde Abhandlung der Kaiserl. Universität zu Dorpat


Pargasite
Finland
Länsi-Suomen Lääni, Turku-Pori, Pargas (Parainen), Limberg quarry

Pargasite FOV 8mm© jo-esche 2007


The Limberg quarry is the only quarry in operation today, and pargasite can be found embedded in calcite here also today. It is believed that the quarry operations here might have started as early as the 12th century, and that the total production is estimated to be approaching 100 million tons.

Literature:

K. Puustinen (1999): Distribution and production of Finnish limestone mines. Geological Survey of Finland.


Pargasite
France
Auvergne, Haute-Loire, Lavoûte-Chilhac, Saint-Privat-du-Dragon, Peygerolles

Pargasite 1,4mm crystal© François Périnet
Pargasite 0,4mm crystal© François Périnet

The pargasite from the outcrop at Peygerolles occurs as mm sized crystals in a corundum and sapphirine bearing amphibolite. This rather special amphibolite is found on the contact between two major units in a metamorphosed ophiolite. The pargasite is formed by the influx of Al rich fluids during the metamorphosis.

Literature:

J. Berger, O.Femenias, D.Ohnenstetter, G. Plissart, J.-C.C Mercier (2010): Origin and tectonic significance of corundum–kyanite–sapphirine amphibolites from the Variscan French Massif Central, Journal of Metamorphic Geology
Volume 28, Issue 3, pages 341–360.

J. Berger, O.Femenias, J.-C.C Mercier, D. Demaiffe. (Ocean-floor hydrothermal metamorphism in the Limousin ophiolites (western French Massif Central): evidence of a rare preserved Variscan oceanic marker. Journal of Metamorphic Geology Volume 23, pages 795–812


Pargasite
Germany
Rhineland-Palatinate , Eifel Mts , Daun , Brück-Dreis, Dreis Maar (Dreis pond)

Pargasite 8cm megacryst© 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.

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 large, well formed crystals embedded in the lava rocks.

The amphiboles from the Eifel area can be either pargasite, kaersutite or titanian magnesiohastingsite, and titanian pargasite seems to be the most common.

Literature:

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


Ferropargasite
Italy
Campania, Naples Province , Somma-Vesuvius Complex , Monte Somma

Ferropargasite 10mm crystal © C.H.M.-Schäfer
Ferropargasite 20mm crystal © C.H.M.-Schäfer

The Somma-Vesuvius is a composite central volcano composed of an ancient stratovolcano, Mount Somma, and more recently by a cone, the Vesuvius. The age of the oldest outcrop is about 25,000 years.The latest round of activity seems to have ended with the eruption of March 1944. This eruption was the beginning of a resting phase characterized by modest signs of seismic activity and fumarole (Arno et al., 1987).
More than 230 species has been found in this area, and is one of the most interesting places in Europe. There are in principle four different mineral forming environments, each with a different mineral assemblage;
I. Minerals that are found in the ejected limestone blocks of Monte Somma.2
II. Pneumatolytic minerals formed in cavities of leucotephrites and conglomeratic blocks ejected by Monte Somma and Vesuvius, or coating the walls of ancient lavas.
III. Fumarolic products.
IV. Minerals that occur as rock constituents of Vesuvius and Monte Somma.
Amphibole minerals can be found in all of these mineral forming environments.

The two pictured ferropergasite specimens are associated with Sanidine XX and Nepheline XX in a vug of an ejected limestone (left image) and as rock forming Ferropargasite embedded in coarse-grained Sanidine matrix (Sanidinite ejectum), associated minerals are Andradite/Grossulare and an altered Wöhlerite/Hiorthdahlite

The identity of the pictured specimen is confirmed by EMPA and their composition is close to the join Ferropargasite/Potassic-Ferropargasite, with a measured Na:K-ratio about 6:4. ( Personal Communication C. Schäfer, 2011).

Literature:

Russo, M., Punzo, I., (2004): I minerali del Somma-Vesuvio. AMI (Italian Micromineralogical Association), Ed., Cremona.

A. Pelloux, (1927): The minerals of Vesuvius. American Mineralogist Volume 12, pages 14-21.

A. Pecerillo, (2005): Plio-quaternary volcanism in Italy, Springer Verlag


Ferropargasite
Pakistan
Northern Areas , Baltistan, Skardu District, Shigar Valley,

Ferropargasite 10,5 cm crystal © H. Obodda


These amphiboles are most likely found in metamorphic rocks of greenschist to upper amphibolite facies. Minerals from these rocks are extracted in the lower Shigar Valley Area, normally in the Alchuri or Hashupa valleys where several different minerals occur in alpine cleft type environments.

Actinolite is fairly common in these clefts, but are generally from light to dark green, and is often found as inclusions in other minerals. These darker large amphibole are much rarer than the lighter, green actinolite crystals, and are generally considered ( finds from around 2000) as ferro-actinolite. The pictured amphibole was found in 2007, obviously from another cleft, and may well be a different species than the others.

I have not found any analytical data or literature references supporting the identification of these dark amphiboles as neither ferro-actinolite nor ferropargasite.

Literature:

Wilson, Wendell E. (2006): Minerals from Alchuri.(Pakistan). The Mineralogical Record, November issue

Hassan, Muhammad. (2007):Mineralogy and Geochemistry of the gemstones and the gemstone baring pegmatites in Shigar Valley of Skardu Northern Areas of Pakistan. Thesis for the Degree of Doctor of Philosophy in Geology, National Centre of Excellence in Geology University of Peshawar.


Pargasite
Pakistan
Northern Areas , Gilgit District, Haramosh Mts.

Pargasite 6,2 cm specimen© Rob Lavinsky


The intense green pargasites from Northern Pakistan are amongst the most desirable amphiboles for collectors and good specimens can reach into the 4 digit USD price range on the retail marked. The pargasite is found associated with the ruby bearing marbles in the Baltit metasedimentary group, and pargasites can be found in several outcrops in this rock.

This group is contained in the Karakorum methamorphic belt, and pargasite ( and ruby) locations belonging to this group surfaces in a more than 100km long belt all the way from Afghanistan through Pakistan to India. The Haramosh mountains lies just south of the Hunza valley( see next location), but it is a bit misleading to attribute pargasite to a Haramosh monitain location. Reason being that the mountains lies south of the main Karakorum thrust, and the intense green pargasites are only found in the Bilbit group marbles north of the main Karakorum thrust.

These pargasites are sometimes referred to as “Hunza emeralds” due to their beautiful green color. This is obviously misleading, and inexperienced buyers may easily be confused as real emeralds are found in a talc carbonate rock in the Haramosh mountains. Both emerald and green pargasite may be offered in the same mineral markets as emeralds

Literature:

Experts Advisory Cell, Ministry of Industry and Production (2004): Investment oriented study on minerals and mineral based industries, Government of Pakistan

Jim Clanin (2008): Gemstone and mineral mining in Pakistan’s mountains, InColor

Eldridge M. Moores,Rhodes Whitmore Fairbridge (1997): Encyclopedia of European and Asian regional geology. Chapman & Hall


Pargasite
Pakistan
Northern Areas, Gilgit District, Hunza Valley, Aliabad

Pargasite 1,7 cm crystal© KhyberMinerals.com


Pargasite 16mm crystal©
Pargasite 3,4 cm crystal© Russell G. Rizzo


Pargasite 1 cm crystal© Rob Lavinsky
Pargasite 1,5 cm crystal© Rob Lavinsky

The mineral locations in the Hunza Valley were discovered in the 1970-ties during construction of the Karthoum Highway. As the minerals ( in particular ruby, but also pargasite and others) proved a valuable source of hard cash, and are extracted from several locations near Aliabad, which is the local mineral market place. In this context, “near” is a relative term as the area is very rugged and many of the locations are rather remote and difficult to access.

The pargasite normally occurs as attractive grass green irregular crystals in a white marble host rock, well developed, and/or transparent crystals are rare but can be found. It seems that the crystals does not ( or very rarely) exceed 5cm length in the longest direction. Garnier et.al. has analyzed this pargasite and found a small ( 0,11-0,34 %wt) Cr2O3 content, which should be responsible for the attractive color.

The geologic history in the area is complex, and is discussed in detail in several publications. The pargasite bearing marbles are found as concordant intercalations within sillimanite- and garnet-bearing gneisses and micashicts crosscutted by leucogranittic aplites and granite pegmatites. It is believed that the chemical elements required to form pargasite and the other minerals has been contained within the original carbonate sediments as aliminous clays and organic matter, and that the pargasites has been formed by regional metamorphosis (amphibolite phasis) in the Indo-Asian plate collision.

Literature:

Jim Clanin (2008): Gemstone and mineral mining in Pakistan’s mountains, InColor

M.Okrusch, T.E.Bunch, H.Bank (1976): Paragenesis and Petrogenesis of a corundum-bearing marble at Hunza (Kashmir). Mineralium Deposita 11

Virginie Garnier, Gaston Giuliani, Daniel Ohnenstetter, Anthony E. Fallick, Jean Dubessy, David Banks, Hoàng Quang Vinh, Thérèse Lhomme, Henri Maluski, Arnaud Pêcher, Kausar Allah Bakhsh, Pham Van Long, Phan Trong Trinh and DietmarSchwarz (2008): Marble-hosted ruby deposits from Central and Southeast Asia: Towards a new genetic model, Ore Geology Reviews 34 (2008) 169–191

M. Qasim Jan and Ali H. Kazmi (2005): PLATE TECTONIC CONFIGURATION OF GEMSTONES OF PAKISTAN, 1st Kashmir International Conference, 20-21 September, 2005; University of AJK, Muzaffarabad.


Pargasite
Pakistan
Northern Areas, Gilgit District, Hunza Valley, Aliabad, Ganesh

Pargasite 1,5 cm crystal©
Pargasite 1 cm crystal© Rob Lavinsky

Ganesh is one of many pargasite locations near Aliabad.


Pargasite
Russia
Eastern-Siberian Region, Prebaikalia (Pribaikal'e), Irkutskaya Oblast', Lake Baikal area, Slyudyanka (Sludyanka)

Pargasite 3 cm crystal© Constantin Klopotov
Pargasite 3 cm crystal© Constantin Klopotov

The crystalline rocks of the Slyudyanka group are Upper Archaean carbonate and quartz/diopside rocks that has undergone a series of metamorphic and metasomatic events. A wide range of minerals has been found in the mines and quarryes exploiting industrial minerals ( phlogopite, marble, lazurite, wollastonite) since the 18th century. The skarns has been extensively studied by Russian scientists and both contact skarns and vein skarns are known.

Well formed and terminated pargasites areknown in crystals up to 10х8х3 сm: (Pavel M. Kartashov analytical data, 2011)

Literature:

D.H.Mikhailov, V.YA.Khiltova (1997): Khamar-Daban and Pre-Olkhon inliers(SW Prebaikal). Precambrian ore deposits of the East European and Siberian cratons (Dmitriĭ Vasilʹevich Rundkvist,Con Gillen ed.) Elsevier Science BV.


Pargasite
Sri Lanka
Southern Province, Embilipitiya , Kollonne village

Pargasite 3,8 cm specimen © fabreminerals.com


The shiny, black and slightly rounded amphibole crystals from this location is found in a calcite skarn with gem olivine (tradename dunilite) . The location was discovered in 1996 and has been worked with handtools primarily for olivine. By 2000, the site was blasted to a 3 m deep hole, 5m long and 3m wide.

The amphibole was tentitively named edenite/ferrohornblende in the original description of the locality (Burford,Gunasekera) based on the refractive index and specific gravity of the amphbole. Mindat uses Mineralogial Record(2001) as reference for naming this amphibole pargasite.

literature:

Burford .M., Gunasekera ,D.P.,(2000) An unusual olivine group of gemstone from Kolonne, Sri Lanka.Trade name Dunilite.

Galser S.I., Gunasekera .D.P.,(2005) Rare Dunilite from Kolonne , Sri Lanka, Midlands focus,


Ferropargasite
USA
New York, Essex Co, Keene, Cascade Slide

Ferropargasite © 2008 Peter Cristofono


The ferropargasite has been found in the Cascade Slide on the north slope of Mount Cascade in the Adirondack mountains. Ferropargasite is found in marble and calc-silicate xenoliths in an anorthosite massif. The anorthosite formed during the Grenville orogony, and it is believed that the metasedimentary xenoliths formed near the top of the anorthosite intrusion, and is relatively common near mountain tops in the area.

The largest marble xenolith in the Cascade Slide is 200x30m and has an interesting mineralogy. The ferropargasites can be quite large (~ 10cm) well developed flattened crystals.

Literature:

J.W. Valley and E.J. Essene (1980): Akermanite in the Cascade Slide Xenolith and Its significance for Regional Metamorphism in the Adirdondacks. Contributions to Mineralogy and Petrology no. 74, 143-152

Marian Lupulescu (2008): Amphibole Group Minerals from New York State. Rocks & Minerals, Volum,e 83 May/June.


Pargasite
Vietnam
Yenbai (Yen Bai) Province, Luc Yen

Pargasite 6,9 cm specimen © Rob Lavinsky
Pargasite 5,4 cm specimen © Rob Lavinsky

Pargasite 14,2 cm specimen © rare-X.com
Pargasite 1 cm crystal ©

The Luc Yen pargasites are found in ruby deposits in the Lo Gam zone in a thick metasedimentary sequence of Cambrian age, composed of marble and overlying sillimanite– biotite – garnet schist. These units are intruded by granitic rocks and related pegmatites of Triassic age. The marble are believed to be formed by clay embedded limestones, where the clay minerals has provided the required aluminium and silica to form the pargasites. The formation and occurance of the Vietnamese pargasites are similar to the Burmese and Pakistani occurances.

This location occationally produce som amazing green pargasite/red spinel in a white marble matrix combo specimens. Well formed pargasite crystals to minimum 3 cm are known from Luc Yen.

The Luc Yen deposits was not discovered until the 1980-ties.The pargasites was first brought to market in China, and was consequently believed to be of Chinese origin. The green pargasites from Luc Yen have been claimed to be fluor-cannilloite, but there are no analytical evidence whatsoever to support this claim. See also Mindat mistakes and errors forum.

Literature:

V. Garnier, D.Ohnenstetter, G Giuliani, H. Maluski, E. Deloule, T.Phan Trong, L. Pham Van, V Hoang Quang (2005): AGE AND SIGNIFICANCE OF RUBY-BEARING MARBLE FROM THE RED RIVER SHEAR ZONE, NORTHERN VIETNAM, The Canadian Mineralogist Vol. 43, pp. 1315-1329

C. A. Hauzenberger, T. Häger, W. Hofmeister, V.X. Quang, G.W.A.Rohan Fernando (2003): Origin and formation of gem quality corundum from Vietnam, "Geo- and Material-Science on Gem-Minerals of Vietnam" Proceedings of the International Workshop, Hanoi, October 1 - 8, 2003

Olav Revheim, August 2011

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Edited 34 time(s). Last edit at 03/25/2012 07:19PM by Olav Revheim.
avatar Re: Pargasite series
June 16, 2011 07:09AM
Olav, Good start.

Rock Currier
Crystals not pistols.
avatar Re: Pargasite series
June 28, 2011 10:30PM
    
Ferropargasite from Portugal is more similar to actinolite. Apparently this is result of wrong determination of skillful dealer of Martins da Pedra.

Here are two not the biggest, but well formed and terminated pargasites from Slyudyanka skarns, where were known its crystals up to 10х8х3 сm:
[www.mindat.org]
[www.mindat.org]
Re: Pargasite series
June 29, 2011 05:56PM
    
Thank you Pavel,

I have added the Slyudyanka locality as you suggest. I also could only find references to actinolite from the calc-silicate/skarn rocks of the Cala mining district and I have consequently removed the entry.

Thanks

Olav
avatar Re: Pargasite series
August 25, 2011 02:06AM
Olav,
An excellent job. I read it over and corrected a few typos. Usually I find more in rereading my own stuff. I think you can take the First Draft off the top of the article.

Rock

Rock Currier
Crystals not pistols.
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Mineral and Locality Search
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