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Density:                       3,2            Streak:        White   
Cleavage:        Perfect            Composition:    silicate    LiAlSi2O6

Spodumene is derived from the Greek word “spodoumenos”, which translates to “burnt to ash”, which refers to the ashy colour of early specimens.  Spodumene is a relatively new mineral having been discovered in the last 300 years, and gem varieties have only been discovered in the last 130 years.

Crystals are prismatic, generally flattened and elongated and the termination is usually rounded. Crystal faces are often pitted and rough. The largest crystal ever mined was from the Etta Mine, Keystone, South Dakota, USA and measured 14,35 m X 0,8 m. Yes, that is metres! Weighing about 90 tons, it is a real heavy weight. Good luck with placing that in your display cabinet!

Spodumene is mined as a source of lithium although the latter only comprises 3,73 % of its molecular weight. Its refraction index is 1,66. Prism faces are deeply striated lengthwise and clear colourful varieties show strong pleochroic colour intensity variation when a crystal is viewed along the various axes. Other associated minerals include lepidolite, feldspars, quartz, tourmaline and topaz.

Spodumene is found in three gem varieties: kunzite, hiddenite and triphane.

Kunzite is the pink to light purple variety which was first found in the pegmatites of Pala, California, in 1902, and is named after the famous mineralogist George Frederick Kunz (1856 – 1932) who first identified it. It was not until the 1990s that this gemstone became a more mainstream gemstone, having been used only as a collector’s gemstone prior to that time.

Although kunzite is a very attractive pink gemstone, it does unfortunately have the nasty habit of colour fading after prolonged exposure to bright light and sunlight. Although the colour-fading effect is very slow, most people prefer to wear it in the evening to avoid sunlight exposure and it is, therefore, regarded as an “evening” stone for that reason.

Kunzite deposits are wide spread over the world with large deposits which makes it more affordable than most of the other traditional gemstones. Very large flawless crystals have been found, from which very large flawless faceted gemstones can be cut. The “Big Kahuna” for example measures over 30 cm in height.

Most kunzites in their natural form are very light in colour, and are commonly heat treated to intensify colour and remove brownish tones.

Kunzite is found in Afghanistan, Brazil, Canada, Finland, Madagascar, Mozambique, Nigeria, Pakistan, Sri Lanka and the USA.

Hiddenite is the less common pale-to-emerald green gem variety of spodumene. The first specimen of hiddenite was recovered in 1879 near the tiny settlement of White Plains, west of Stony Point, Alexander County, North Carolina. It is told that a young man named Lackey brought some specimens to J. Stephenson, a local trader who was also a keen mineral collector. He initially thought it was diopside. He in turn brought the discovery to the attention of exploration geologist William Earl Hidden, who had been commissioned by Thomas Edison……………that rings a bell, or rather sheds more light on the matter………..to search for any sources of platinum in North Carolina which was according to the reference source “stunningly unsuccessful”. Hidden sent some samples to J. Lawrence Smith, a well-known chemist and mineralogist. Smith correctly identified the specimens as being a variety of spodumene and named it “hiddenite” in honour of William Hidden. The settlement in which it was found was also later renamed to “Hiddenite”. The town was, therefore, named after the mineral and not the other way around, which is normally the case with the naming of new minerals. In the hey-days of the hiddenite mining during the 1880s to 1890s it was also referred to as “lithia emerald” and “Carolina emerald”.

One of the important mines in the above mentioned area is the Emerald Hollow Mine. This is the only emerald mine in the USA which is open to the public to search for emeralds. At the mine, more than 63 different types of gems and minerals can be found including emeralds, amethyst, sapphire, aquamarine, topaz, garnet, as well as hiddenite….So! Who’s game for a club outing?

In addition to the above mentioned type locality, hiddenite is also mined in Afghanistan, Brazil, China, Madagascar and Sri Lanka. A hiddenite crystal of 25 cm, weighing 7 500 carats, was found in Afghanistan.

People disagree about exactly what hiddenite is. Some are of the opinion that it must contain chromium, which is responsible for the brilliant deep green colour. Others say it must be a particular shade of green, and others claim that to be regarded as true hiddenite, it must come from the Hiddenite area, of North Carolina where it was discovered.

Hiddenite is generally not treated or enhanced, though deep emerald-green hiddenite can be formed through irradiation of other lighter forms of spodumene. Natural hiddenite from North Carolina is very rare and increasingly difficult to obtain.

Triphane.    Not much is mentioned about triphane, possibly because its colour, which varies between colourless and yellow, is less attractive than the pink and the greens of kunzite and hiddenite respectively.

Kunzite, hiddenite and triphane are however difficult to facet due to the perfect cleavage and splintery nature of the gemstone. It is very sensitive to knocks and will chip if hit or knocked too hard. Small gemstones are not commonly cut from the stone due to the perfect cleavage and strong pleochroism. For this reason, it is cut to show the deepest pink colour from the top of the gemstone. It is mostly used as a pendant stone and as a large decorating stone on ornamental objects. It is less commonly used in rings, necklaces, or other items where small stones are required.

On the local front only spodumene is found and unfortunately not the gem varieties. It is mined in some pegmatites in the Northern Cape where crystals can be several metres long. It  occurs at Spodumene Kop, Norrabees (as referred to in Charlie’s article “Norrabees – Lepidolite and Spodumene - the lithium bearing ores” also included in this month’s newsletter), Noumas and Henkries in Namaqualand.

It is also found in the Piet Retief district, Mpumalanga, the Free State in the south-eastern section of the Vredefort dome and in KwaZulu-Natal north of Port Shepstone. Spodumene is also found in our neighbouring countries, i.e. Namibia, Zimbabwe and Botswana.    JDJ

 

Photos of various specimens from Afghanistan: From left to right: triphane (11 cm x 2,5 cm), “hiddenite” (9 cm x 3,5 cm), lilac kunzite (5,4 cm x 3 cm), pink kunzite (5,3 cm x 3 cm), pink kunzite (5,2 cm x 2,5 cm)

                                                             

References
Cairncross, Bruce, 2004 – Field Guide to Rocks & Minerals of Southern Africa.
webmineral.com
www.galleries.com
www.giantcrystals.strahlen.org
www.minerals.net
www.mindat.org
www.wikipedia.org       

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RECENT FACETINGS BY DUNCAN MILLER


Despite leading a full working life, and on Saturdays teaching club members theoretical mineralogy, gemmology and practical faceting, Duncan is busy at his own faceting machine in his spare time. He has produced the following marvellous stones. The kunzite was faceted some while ago but is topical to our lithium theme this month, and the morganite collection, cut all from one choice stone, is fresh off the lap.

1. The kunzite (spodumene) crystals are 5,5 cm and 3,5 cm long respectively. The left hand one shows the typical purplish-pink colour and the right hand one the characteristic striations on a naturally etched crystal. (It also happens to be twinned, but you can’t see that in the photograph because the twin plane is parallel to the plane of the photo.)

2. The faceted kunzite is a Barion cut, with a mass of 12,26 ct. It has tiny bubble inclusions, which in reality are hardly visible but annoyingly are picked up selectively by the camera.


                                      
3. BELOW    The pear-shaped morganites (beryl) range in mass from 59,58 ct to 7,60 ct. The morganite briolettes are 51,28 ct and 51,21 ct, and are each 40 mm long. All the morganites were cut from a single 208,2 gram rough crystal belonging to Lorna Quinton.
 


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Norrabees - Lepidolite and Spodumene - the lithium bearing ores.

About 10 years ago, before I was a member of the Club, a few friends and myself proceeded to Steinkopf to look for “rocks” with the help of a GPS and information gathered from Geoscience data. The highlight of the trip was Norrabees 1. As we approached the koppie there was this soft purplish gash running from the crest to the base. Five excited, green-behind-the-ears, rock aficionados poured out the 4x4 and soon were scrambling around the lepidolite and spodumene slopes with oohs and ahs. When the first watermelon tourmaline turned up the hunt intensified. Then someone found some botryoidal spodumene amongst the lepidolite. Crystals!!! Finally, in a shallow cave that substituted as a mine, John Graham discovered some gemmy needles of hiddenite in situ.

Later in discussion with George Swanson, we asked why all this material was abandoned. He mumbled something about lithium and that the Chinese were not interested. Lepidolite is a micaceous mineral containing lithium. Spodumene is a lithium aluminium silicate. A single crystal of spodumene was found in a South Dakota mine that was 15 metres long and weighed ten tons. Even the green tourmaline has a smattering of lithium in it. Most of the lithium mined today comes from lake brines which means, that to obtain the concentrate, water is merely evaporated and the various salts cheaply separated. Chile is the main exporter. Economically Norrabees could not compete.

On working with the lepidolite from Norrabees in our workshop we found that it was too micaceous but the lapidarists loved the colour. We thus located some acceptable rough which produced some quite decent cabochons. There is a project now on to make eggs and then possibly spheres. The spodumene has badly weathered and as soon as you touch it with a machine it breaks into smaller and smaller chunks.

Lithium, being the lightest metal, produces very light alloys and it also strengthens the alloy. Thus it is used in armour-plating. In World War 1, Germany was blockaded and so couldn’t get tin. They made an alloy of lead, lithium and a few other minor ingredients called Bahnmetal as a substitute for tin which is still in use today.

The hydrogen in the hydrogen bomb is lithium hydride which is wrapped around an atomic bomb. To add insult to injury, the whole contraption is mounted in a casing with uranium imbedded. You thus have three explosions in one. All devastating and frightening, and that is why lithium production in nuclear countries is not published.

Of course we all know of our long-lasting lithium batteries and so to end on a cheery note, it was discovered in 1945 that lithium carbonate helps to cure manic depressives and was used extensively. With the world’s economy as it is, look after your lepidolite carefully.

Finally, lithium is an amazing element. In the universe it is not being produced anymore. For some obscure reason this element gets bypassed during a supernova and all that exists was manufactured during the Big Bang, or Small Bang, or other, whichever theory you subscribe to. So, again, hold onto your lepidolite. Lithium is getting more, and more, scarce with each passing day.  Charlie Scharfetter.