Much ado about Tantalum. Again.,  by Richard Burt**, Consultant. Elora, Canada in pdf format. (2.1 MB)

Tantalum was first isolated as a discrete element in 1802, by Anders Ekeberg, who wrote “This metal I call tantalum … partly in allusion to its incapacity, when immersed in (many) acids, to absorb any and be saturated” – a reference to Greek mythology, where Tantalus, as a punishment for several heinous acts, was condemned to stand in water, under a fruit tree, but never be able to reach the fruit nor drink the water.

Compared to the ‘major’ metals, the tantalum industry is tiny: total world mine production rarely exceeds 2000 metric tonnes of contained Ta₂O₅ a year, which equates to an annual value, at today’s prices, of about US$300 million, less than 1% of the value of world’s copper output.

Tantalum is not traded on the L.M.E. – or any other exchange. Prices are set – either on long term contracts, or parcel by parcel – between miner or trader and processor, on a confidential basis. Even the industry body, the Tantalum-Niobium International Study Center which collects, collates and publishes data on volumes of material as it passes through the supply chain, is by its mandate, and for anti-trust reasons, prohibited from collecting, publishing, or even discussing current and future prices.

There are relatively few industrial mines. Classically these sold their output to only a handful of chemical processors (colloquially often known as smelters). In addition, a not insignificant amount of material is won by artisanal means. Here the rough product passes through several hands that upgrade and blend small packages, prior to international traders selling these to the processors. None of these artisanal mines are, of themselves, of any significance, but as a whole they make up an important part of the market, in that they can come ‘on stream’ or shut down at a moment’s notice. Processors sell their product to a variety of customers who fabricate it into something else (for example, capacitors, bar, rod, etc.) which are then sold to manufacturers for integration into their products.

Market confidentiality, artisanal mining, convoluted supply chain. Add to this, that one of tantalum’s major uses is in the electronics industries, and it is little surprise that a decade or so back some civil societies decided the tantalum used in cell phones would be the ideal target for their campaigns to alert the 1st world to the horrendous civil strife in central Africa. Right campaign, wrong target, as this paper will show. The paper will also show that, while industrial mine production dropped dramatically after the 2008 recession, it is recovering, as old mines are restarting and new ones are close to coming on stream.

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**Richard Burt worked in the Cornish tin mining industry for 12 years before emigrating to Canada in 1977. From 1977 to 2007 he was Mill Superintendent, then, from 1983, General Manager at Tantalum Mining Corporation of Canada (Tanco). He subsequently moved to Tanco’s parent company, Cabot Corporation. as Director of Mineral Development, with a world-wide mandate primarily involved in tantalum at that time. In 2002 he set up his own consultancy, specialising in gravity concentration and various aspects of the tantalum industry, with an international client list. Burt was awarded the Selwyn Blaylock Medal in 1998 for services to Canadian industry. He was an overseas member of the council of the IMM 1998-2003 and president of the Tantalum-Niobium International Study Center from 2009-11. Since 2009 he has been heavily involved in the central African conflict minerals issue.

A washing area at a typical artisanal mine, Katanga, DRC. (Picture courtesy K. Hayes)

Poster: Mineral geochemistry and petrogenesis of granitic pegmatites in the Fregeneda-Almendra area (Spain and Portugal), by Vieira, R., Roda-Robles, E., Pesquera, A., and Lima, A.

Poster: Mineral geochemistry and petrogenesis of granitic pegmatites in the Fregeneda-Almendra area (Spain and Portugal)  in pdf format:
Vieira_et_al_Hutton_2011 (12.4 MB)

The Fregeneda-Almendra pegmatite field (Spain-Portugal) is characterized by the occurrence of numerous pegmatites of different types. Most of these pegmatites are barren, but Li- and/or Sn-rich bodies are also abundant in the northern part of the field. These pegmatites intruded mainly the Schist- Greywacke Complex, north of the syn- to late-Variscan Mêda-Penedono-Lumbrales leucogranite complex (MPL). They show a zonal distribution with the degree of evolution increasing northwards relative to the MPL. In order to shed light on the genetic relationships between granites and pegmatites in the FA field, representative micas from the muscovite-lepidolite series were separated from the different pegmatite types, as well as from the MPL granitic complex and from another granite detected by drills in the north of the area. These mica samples have been used to date their hosting rocks by the step-heating ⁴⁰Ar/³⁹Ar method. Moreover, a geochemical modelization has been made in order to define the possible evolutionary trends, and the petrogenetic affiliation of the different pegmatite types, as well as the relationships between the pegmatites. A first event of pegmatite formation would be related to the crystallization of the syn- to late-D3 Variscan MPL granitic complex. The trace-element modeling shows that lower rates of fractional crystallization, from a melt with similar composition to the MPL, would originate the barren intragranitic pegmatites and the granitic apophysis that outcrop close to the MPL, whereas higher degrees of fractional crystallization would be related to the origin of the Sn-rich dykes of the Feli open pit. These bodies, with plateau ages ranging between 300.0 ± 3.5 to 304.8 ± 4.4 Myr, intruded S3 tectonic foliations (N100-120E) and are connected to the Variscan polyharmonic folding and to the MPL emplacement. The generation of some conformable metamorphic and granitic-pegmatitic segregations that outcrop in the proximities of the MPL, considered to form part of the Alamo Complex, would be coetaneous or preceding this process. The discordant intermediate and the Li-rich pegmatites represent highly differentiated melts, enriched in rare-elements, especially lithium. They infill late-tectonic Variscan sinistral structures (NNE-SSW and NE-SW), with plateau ages ranging from 295.1 ± 4.2 to 296.4 ± 3.5 Myr. The trace-element modeling demonstrate that these pegmatites would be related to high rates (≥ 90%) of fractional crystallization from melts with compositions analogous to the late- to post-D3 Variscan granites, e.g., Saucelle or Villar de Ciervo granites, respectively. However, the difference of 10 Myr in the age between the late-D₃ Variscan granites and these pegmatites, exclude those granites as potential generators of the Li-rich pegmatites. Accordingly, the evolved pegmatites could be related to a late-Variscan (300 to 280 Myr) non-outcropping granite as a result of high rates (≥ 90%) of fractional crystallization.

Field Course on the Rare Element Pegmatites of Madagascar, June 11 – 22, 2001, Antananarivo, Madagascar.

Organized by Museum of Natural History, Milan (Italy), University of New Orleans, Dept. of Geology & Geophysics (LA – USA) Direction of the Geological Survey, Ministry of Energy and Mines, Antananarivo (Madagascar) with the collaboration of ATPEM (Assistance Technique aux Petits Exploitants Miniers), Direction des Mines et de la Géologie, Antananarivo (Madagascar) Gondwana Gems, Antananarivo (Madagascar).  Organizing Co-Sponsors: S.N.T.P. International, Group CFE, Antananarivo (Madagascar).  UNESCO-IUGS-IGCP.

Technical Program And Field Trip Guidebook  in pdf format: text (194K)

figures 1-5 (173K) figures 6-11 (203K)

Active Gem Mining at the Cryo Genie Pegmatite Mine, southern California

by Jim Clanin, JC Mining (Reports 1-8); Kenneth L. Gochenour (Report 9)

in pdf format:

Report 1 (Aug 1, 2002): text + 3 figures (180K)

Report 2 (Sept 1, 2002): text (56K)

Report 3 (Sept 7, 2002): text + 2 figs. (108K)

Report 4 (Sept 13, 2002): text (48K)

Report 5 (Sept 21, 2002): text (83K)

Report 6 (Sept 29, 2002): text + 3 figs. (560K)

Report 7 (Oct 27, 2002): text + 2 figs. (150K)

Report 8 (Nov, 2002): text + 2 figs. (132K)

Report 9 (Sept, 2002): text + 4 figs. (180K)

Application of Ground Penetrating Radar (GPR) at the Cyro-Genie Gem Pegmatite Mine, San Diego County, California

by Jeffrey E. Patterson, University of Calgary, Calgary, AB, Canada.

Mining continues through 2003 at the Cryo-Genie mine, near Warner Springs, California, and large, crystal-filled miarolitic cavities are still being discovered. To aid in the exploration for pockets, Jeffrey Patterson conducted a survey by ground penetrating radar (GPR), and his recently published report is available here in pdf format:
text 25 pages + 40 figs. (1.7 MB)

Patterson, J.E., 2003, Application of Ground Penetrating Radar (GPR) at the Cryo-Genie Gem Pegmatite Mine, San Diego County, California, in: Murbach, M.L., and Hart, M.W., eds., Geology of the Elsinore Fault Zone, San Diego Region, San Diego Association of Geologists / South Coast Geological Society 2003 Field Trip Guide, Hot Springs and Tourmalines of Eastern San Diego County, Ô31, 45-62.

Petrography and Geochemistry of the Li-F Granites and Aplite-Pegmatoid Banded Rocks of the Orlovka and Etyka Tantalum Deposits in the East Transbaikalia

by G.P. Zaraisky (1), R. Seltmann (2), V.V. Shatov (3), A.M. Aksyuk, Yu.B. Shapovalov (1), and V.Yu. Chevychelov (1)

(1) Institute of Experimental Mineralogy (IEM), Chernogolovka, Moscow District, Russia

(2) GeoForschungZentrum (GFZ), Potsdam, Germany

(3) All-Russia Geological Research Institute (VSEGEI), St. Petersburg, Russia

in pdf format: text + 5 figures (472K)

Mining News from Mt. Mica, Maine – 2004

Gary Freeman

in pdf format: text + 11 figures (450K)

Mining News from Mt. Mica, Maine – 2006

Gary Freeman

in pdf format: text + 8 figures (4.4 M)

Recent Finds From the Dudley Granite-Pegmatite Body, Kangaroo Island, South Australia
(Text by David London)

Rob Cameron (ebonyridge@hotmail.com), the exploration manager for South Australia Lithium, and Patrick Gundersen (patrick@folk-stone.com), a gem prospector, have provided the following information and photos of recent finds (2015-2019) at the Dudley granite-pegmatite, located at the northeast end of the Dudley Peninsula, Kangaroo Island, South Australia (Figure 1). Outcrop is poor (Figure 2), however surface vestiges of the dikes (Figure 3) are traceable for kilometers on strike and meters across. The area is deeply weathered and has been a source of kaolin in the past (see the attached article by Bridget Jolly). Another recent account by Geoffrey Chapman can be found at the website of the Kangaroo Island Pioneers Association (https://www.kipioneers.org/contributions). Both reports indicate that the area has a long history of exploitation for kaolin and feldspar, and that the discovery of gem-quality tourmaline goes back to the turn of the 20^th century. Lithium Australia (https://www.lithium-au.com/) has posted a preliminary survey and assessment of their former leases (attached). The tracts once leased by Lithium Australia are now held by South Australia Lithium.

Mr. Cameron reports that the coarsely pegmatitic portion of the body contains a spodumene-bearing zone. The spodumene found at surface is heavily altered. With the aid of an excavator, Mr. Gundersen uncovered miarolitic cavities lined with smoky quartz crystals along the roof, and with tourmaline along the floor. The cavities are said to be in a granitic material (Figure 4) that is not the same as a layered aplitic body that is associated with the pegmatite. Within the decomposed granite, Mr. Gundersen encountered a body of coarse muscovite that heralded underlying miarolitic cavities. Mr. Gundersen’s finds from 2019 and previous visits include large smoky quartz crystals and gem-quality sections of tourmaline (Figure 5).

To put this find in context, Western Australia is home to many granitic pegmatites that have been mined for feldspar, lithium, tin, tantalum, and cesium. Occurrences of gem-quality minerals, however, are rare. Mark Jacobson (personal communication via email, October 2023) cited a half dozen other occurrences of gem minerals in pegmatites, mostly in WA. A plethora of granites from Victoria through New South Wales to Queensland do not have any associated pegmatites. Their mineralization is limited to tin-tungsten quartz veins. Gem-quality sapphire, ruby, and zircon are produced from near Inverness, NSW, but in these deposits the gem crystals occur as xenocrysts (inherited from other source rocks) in basalt. Australia is, of course, home to many diamond localities, the most famous of which is at Argyle, WA. Among the known pegmatitic sources, the deposits on Kangaroo Island appear to have considerable potential for gem tourmaline.

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