Re: Thortveitite

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Thortveitite
(Sc,Y)₂[Si ₂ O₇] Monoclinic


Thortveitite is a member of the thortveitite-group of minerals, with a typical formula of (REE)₂[Si ₂ O₇. Thortveitite was the first mineral described with scandium as a main constituent in the formula, and it is still the most frequently found scandium mineral. It is however a rare mineral, and only a few localities have produced crystals of any size. Including the Y-free variety befanamite, little more than 100kgs of the mineral has been found, most of it from the Evje/iveland district in Norway and the Befanano pegmatite in Madagascar. The locations at Evje/Iveland has produced the largest crystals to date, grayish green crystals up to 35cm, whereas the Befanano crystals are smaller and darker in color. White and blue microcrystals and grains are known from Italy and Kazakhstan. Given the limited number of scandium minerals, and the scarcity of which they occure, scandium is surprisingly abundant in the earth’s crust. Still, all scandium minerals are very rare, and only rarely found in crystals of any size. This is because the scandium ions closely resemples ferric iron, and readily substitutes for this ion in iron bearing, rock forming minerals such as amphiboles and biotite-group minerals.

Thortveitite was first found by Per Schei in the Landsverk 3 quarry, Evje, Norway in 1903, labelled “epidote?” and put in a drawer. Olaus Thortveit was the first person to recognize thortveitite as a potenitally new species based on some crystal fragments found at a quarry in Ljoslandsknipan, Iveland, Norway. Jakob Schetelig in a publication in 1922 mentions that he has measured "part of an about 35 cm crystal with a diameter of 4-5 cm in situ" at this locality. But he also mentions that it was not possible to extract this Thortveitite intact. The holotype material was analysed by Jakob Schetelig in 1910 and published in 1911, given the name Thortveitite to honor Mr. Thortveit for this and other contributions to the mineralogical society. This was not the only honour Olaus Thortveit achieved, in 1914 he donated his impressive mineral collection to the geological museum in Oslo and due to it’s quality he was awarded King Haakon’s Medal of Achievement in Gold.

For a long time, Thortveitite was only known as crystals embedded in quartz and feldspar from the granite pegmatites in the Evje and Iveland area but has now been found at some 30 localities. The mineral occurs in a wide variety of geological environments, including miarolic cavities in granites, aplites and pegmatites, polymetallic ores and skarns, REE bearing quartz veins, metasedimentary rocks, placers and alluvial fans, carbonatites in addition to granitic pegmatites. Seemingly, most of the locations have produced only grains, but some of the miarolitic cavities and some of the granite pegmatites have produced nice crystals.


Thortveitite
Italy
Baveno, Verbano-Cusio-Ossola Province, Piedmont, Italy

The thortveitite is found as small crystals in miarolic cavities in the baveno granite.
We need someone to tell us more about the Thortveitite specimens from this locality.


Thortveitite
Italy
Piedmont, Verbano-Cusio-Ossola Province, Baveno, Oltrefiume, Mount Camoscio, Seula mine (ex Montecatini quarry)

Thortveitite occures in miarolic cavities in the granophyre of Cuasso al Monte, Thortveitite occures with other scandium minerals, such as bazzite and others. Thortveitite occurs as tiny greyish or deep blue crystals. The blue varieties contains 2,8 % MnO, and it is believed that traces of Mn3+ causes the blue colour, as this is a strong colouring agent, also responsible for the purple colour of piemontite. This information is extracted from the article “Cesian bazzite and thortveitite from Cuasso Al Monte, Varese Italy: a comparisation with the material from Baveno, and inferred origin” that was printed in the Canadian Mineralogist vol 38, pp 1409-1418 (2000). This article is available on the internet.

These Italian occurances of thortveitite and other scandium minerals are of great importance in understanding why and how scandium minerals are formed in the earths crust, particularily in granite type magmas. Normally scandium is enriched in Fe and Mg rich environments such as gabbros and norite, and not in granite as for these localities.

At least for the Japanese and Swedish locations, there are found evidence of Sc migrating from a surrounding Fe/Mg rich rock into the granite-pegmatites hosting thortveitite. Given the similarity between the Swedish and Norwegian localities, one should not rule out similar mechanisms for the Norwegian locations:

We need someone to tell us more about the Thortveitite specimens from this locality.


Thortvetite
Japan
Honshu Island, Kinki region, Kyoto prefecture, Ohmiya town, Kobe, Shiraishi-yama, Kobe
Thortveitite occurs as good greenish, light green to light greyish green, vitreous, long prismatic crystals to 4cm long and 5mm thick, in parallel growth in light pinkish feldspar in pegmatite at Shiraishi in Kobe-mura (the type locality for kobeite; now part of Ohmiya). (Sakurai et al (1962) Chigaku Kenkyu, 13, 49-51.) Tin-bearing thortveitite at Ohro (Isanago pegmatite mine). (Yamada et al (1980) Chigaku Kenkyu, 31, 205-222; Yokoyama et al (1993) Analyses of natural minerals by energy-dispersive spectrometer. Bulletin of the National Science Museum, ser.C,19:115-126 (in japanese).) Larger specimens can be seen on display at the Masutomi Museum in Kyoto city. Once in a while a specimen is seen on sale at a japanese mineral show, usually only dull and incomplete (broken) crystals, of far lesser quality than the ones on display in museums, so it seems to be quite rare nowadays
(Alfredo Petrov March 18, 2009 )


Thortveitite
Kazakhstan
Djezkazgan Oblast'; Jezkazgan Oblast'), Zhezqazghan Oblysy (Dzezkazgan Oblast'; Balqash (Balkhash; Karatas; Prebalkhashie) Region, Mointy Railway Station, Mointy (Moyynty), Akkuduk (White Well) occurrence


Akkuduk is raremetal ore occurrence, investigated in 1950s and early 60s. It was discovered because of a high radioactivity anomaly discovered by airplane. The ore body has moshroom-like shape and consists of explosive (?) brecciated felsic rocks cemented by hematite and Ferrithorite. So the locality is Y-Th, not polymetallic. The scandium concentration in the ores is rather low. Thortveitite was found in heavy concentrates from the brecciated ores. Because of its unusual blue colour it was initially identified as corundum. Apparently the mineralogist, who had determined this 'corundum" had work before on the Semizbugu corundum deposit, and made this "identification" by sight. Further investigations showed that mineral is pure thortveitite without any Zr or Y impurities. According my own analytical data it contains only small amount of Yb - other HREE and Y are below detection limits. Coloration of the mineral obviously is connected with very low Mn contents ~0.00n % or less.
[Pavel Kartashov 2009]


Thortveitite
Madagascar
Antananarivo Province, Analamanga Region, Ankazobe Pegmatite Field, Anjozorobe Department, Befanamo pegmatite


This REE-rich pegmatite is considered the "type locality" of the Y-free variety of thortveitite; befanamite. Approximately 50kg of befanamite was produced as a source of scandium. Most of the production was in the early 50-ties when the price of scandium was high.

Anyone that has any knowledge on this location or other such locations are requested to provide more information.


Thortveitite
Norway
Aust-Agder, Aust-Agder, Kåbuland


The greatest concentration of Thortveitite mineralization is found in the pegmatite district of Evje/Iveland where thortveitite has been found in some 20-25 different pegmatittic dykes. After it’s initial discovery, more crystals where found and this quickly drew the attention of the global mineralogical community. It did no harm that specimens with crystals approaching 35 cm length were found, and everyone (read national museums) collecting high end specimens wanted specimens of this new mineral which at that time was the only known scandium mineral. The Natural History Museum in London for instance holds 15 specimens from Evje/Iveland, and the Musee de mineralogie, Ecole des mines de Paris has a 20cm crystal found in the “Rumpetrollsynken” or Landsverk2 quarry. It did not take long before this limited market was satisfied and the market for Thortveitite specimens collapsed. This short period after it’s discovery became locally known as the “first klondyke of thortveitite.”

The second “klondyke” came in the 50-ties. A US gouvernment research project on scandium needed ore, and production from the Befanamo pegmatite in Madagascar, and the pegmatites in Evje/Iveland were the only sources of high graded ore. For a few years the price of thortveitite was higher than the price of gold. 1 gram of thortveitie was sold for 13-14 kr/g (equivalent to approx USD30/g today), whereas the gold price was 8,8 kr/g. When a single blast in Tuptane gave 2,5kg of the mineral, no wonder that some of the miners claimed that they had “CEO like salaries” for a few years. The total production until 1960 was estimated to be approximately 50kgs of thortveitite, this according to Bjørlykke who gathered information from the miners. Given that they were paid by the gram, one should assume that a thorough record was kept. Soon the research program was shut down. Evje/Iveland pegmatite district

When I visited the pegmatites in the Iveland Evje area for the first time in 1964 at the age of 15 and spent a week collecting minerals there, I was told many stories by the locals about finds of Thortveitite during the 1950`ies when it was a very valuable ore of Scandium. One of these stories refered to two school boys who had found a piece of Thortveitite of about 1 kg in the tailings of an old pegmatite quarry when walking home from school. With the prices paid at the time (more than gold...) I am sure they were warmly greeted when returning home that evening.¹
1.Knut Eldjarn, email communication 2009.

Today Thortveitite can still be found, and a number of specimens were brought to the mineral collectors market a few years back. These came from the Kåbuland 1 quarry [www.mindat.org]. The price is still quite high for a dull, brittle, grayish green mineral, from 150 USD and upwards into 4 digits for the best specimens. Still the price is too low and the mineral too rare to make “production” profitable in a high cost country like Norway.

The best quarries for Thortveitite was Tuftane and Steane at the Frigstad farm (with approx 2/3 of the total production), whereas the finest crystals came from Mannekleiv and Eptevann . Crystals exceeding 20 cm were found, embedded in quartz or feldspar. Today Kåbuland is considered the best location. Many of the best locations for Thortveitite were relatively small pegmatites and the presence of and xenotime and zircon ( var alvite) are an indication as to the possible presence of Thortveitite especially if these where combined with a quartz core extending towards the surrounding rock.


Thortveitite
Norway
Aust-Agder, Iveland, Frikstad (Frigstad), Tuftane (Tuftan; Tuptane)


Many theories has been published on why such rare mineral appears quite frequently in large crystal in a small area. On a general basis, scandium is not more abundant in neither the general pegmatittic mass nor the surronding amphibolite. It was long believed that the thortveitite bearing pegmatites was deficient in iron, carrying rutile ( ilmenorutile) as the Ti bearing mineral rather than ilmenite. Ilmenite is however the main lead mineral at Kåbuland and a few other occurances, contradicting this theory.


Thortveitite
Sweden
Lappland, Jokkmokk, Ruoutevare

Several granite pegmatites in Sweden contains thortveitite, and one of the pegmatites in the Ruoutevarre mountains is one of them. This locations contains a 1 by 1,5 km pegmatitic body in a gabbro-rock. Within this pegmatitic body a number of coarsly crystallized pegmatite veins has been worked for quartz. A very distinct element exchange between the surronding gabbro and the pegmatites are observed here. The gabbro close to the pegmatites show a significant enrichment of potassium, causing a biotite replacement of pyroxene/amphibole in the gabbro/pegmatite border zones, and plagioclase enrichment in the graphic granite outer zone of the pegmatites. In addition the gabbro is enriched in Si, Ba and Mn. Ti, Mg, Ca, Sr and scandium has been depleted out of the gabbro with as much as 10-20% of the bulk amount present in the border zones.

The pegmatites are enriched in REE minerals and their composition and structure are remarkably similar to the famous Ytterby pegmatite and the Evje/Iveland pegmatite area.

Thortveitite was discovered here in 1978, as the first find in Sweden. Crystals up to 4 cm has been found, associated with plagioclas feldspar and zircon. Thotveitite is a late forming mineral in the primary pegmatite and occationally embeds zircon crystals. The thortveitite from Ruotevarre is very pure and has a dark green colour and are well crystallized. Twins parallell with (110) is common.


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[Edited by Rock Currier 2009]



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Edited 21 time(s). Last edit at 03/26/2012 06:36PM by Rock Currier.

The Thortveitite article has been revamped and reformatted. I think we need to address a change in our formatting. At the top of each article where we discuss in general specimens of that mineral we need to link the mineral name to that minerals data page. Also, all the localities for that mineral need to be linked to the mindat page for that locality. See the examples above in this revamped article. Do you agree that this will be a usefully addition that will increase the usability of the articles?

Rock Currier
Crystals not pistols.

Aksel Österlöf has been very kind to send me a copy of a 1981 geology exam paper on the minerals found at the Ruoutevare pegmatites by Evy Dagbo and Olof Martinsson. I am very grateful to be allowed to read this excellent paper.

I have made a very brief extract of this paper for the thortveitite article, and Aksel, please let me know how to improve what I have written. Any assistance in improving my english will also be appreciated.

Thanks

Olav :)

I found a great article on the internet for the Italian thortveitite locations.

If anyone has more information on the locations in Madagascar, please let me know. I have not been able to find very much on the net.

If anyone has further information on the localities, any public collections containing specimens of Thortveitie or any "warstories or anecdotes related to this mineral, please let me know through a post here or a PM.

Thanks

Olav

Data from a terminated thread that should not be lost:

Rock,

One correction and suggested additions: The correct spelling of the mineralogist who first described Thortveitite is Jakob Schetelig.
Per Schei found the first specimens ( as mentioned) and it could be added the year: 1903 (he was at the time working at the Mineralogical Insitute in Oslo and died very young in 1905).
As for the size of Thortevitite crystals at Ljosland, Iveland, Jakob Schetelig in a publication in 1922 mentions that he has measured "part of an about 35 cm crystal with a diameter of 4-5 cm in situ" at this locality. But he also mentions that it was not possible to extract this Thortveitite intact.
When I visited the pegmatites in the Iveland Evje area for the first time in 1964 at the age of 15 and spent a week collecting minerals there, I was told many stories by the locals about finds of Thortveitite during the 1950`ies when it was a very valuable ore of Scandium. One of these stories refered to two school boys who had found a piece of Thortveitite of about 1 kg in the tailings of an old pegmatite quarry when walking home from school. With the prices paid at the time (more than gold...) I am sure they were warmly greeted when returning home that evening.

Knut Eldjarn 2010



Akkuduk is raremetal ore occurrence, investigated in 50th-early 60th according to high radioactivity anomaly discovered here from airplane. Ore body has moshroom-like shape and consist of explosive (?) brecciated felsic rocks cemented by hematite and ferrithorite. So the locality is Y-Th, not polymetallic.
Contents of Sc in ores of locality is rather low. Thortveitite was found in heavy concentrates from brecciated ores. According to its unusual blue colour it was initially identified as corundum. Apparently the mineralogist, who had determined this 'corundum" had work before on Semizbugu corundum deposit, and made this "identification" automaticaly. Further investigations had show, that mineral is pure thortveitite without any Zr or Y impurities. According my own analytical data it contain only small amount of Yb - other HREE and Y are below detection limits. Coloration of the mineral obviously is connected with very low Mn contents ~0.00n % or less.
Pavel Kartashov 2009


Rock, Semizbugu was entered - [www.mindat.org]. Corundum from this locality especially as grains of concentrates is VERY similar to thortveitite from Akkuduk.
Pavel Kartashov 2009

I understand you problem. With so many minerals yet to go, I often console myself to creating place holders for them by putting in a picture, even if it is not a very good one and if no picture is available I just put down the little bit I know about the locality and move on to the next locality or mineral. We can't be expected to know everything and if there is one thing this project has taught me its that I really don't know very much. A lot of the kind of data I am trying to capture here is related to the ten questions that I tell the authors here to try and answer. Often this information is not know by mineralogists or geologists, but by the miners that dig the stuff or the field collections that go out there and dig it or the mineral dealers who have bought and sold many specimens from the localities and have often traveled to the localities to buy stuff. These are the people that can really answer the ten questions, and in many cases, especially with old localities, the people who could answer them are no longer with us.

Also keep in mind that as time passes more and more people will see what we are doing here and will offer us information that will be good additions to what we have already done. This is something that we hope future generations of mineralogists, collectors, curators and dealers can use to build upon. We are only laying the foundation and we will be fortunate if we achieve that much.
Rock Currier 2009

Rock Currier
Crystals not pistols.