SPODUMENE [Lithium Aluminium Silicate]

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SPODUMENE [Lithium Aluminium Silicate]

June 01, 2012

Rino Safrizal

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[ Silicates : Inosilicates : Pyroxenes ] LiAlSi₂O₆, lithium aluminium Silicate

Spodumene is a rock forming mineral in granites and pegmatites that bear other lithium minerals. Spodumene is a relatively new mineral to science, being discovered in the last three centuries and gem varieties have only been discovered in the last 120 years. Transparent deeply coloured spodumene has two varieties called kunzite and hiddenite. Kunzite is the more common of the two and is known by most gemstone collectors and fanciers. It is a lovely pink to lilac colour that is unique in the gem kingdom. Hiddenite comes North Carolina and is not well known or abundant. It has an usual green colour that is unlike either peridot or emerald. Spodumene is strongly pleochroic and therefore a gem cutter must take care to orient the stone in the best position for the deepest colour. Spodumene's cleavage, parting and fracture also make it a challenge for any gem cutter.

Physical Characteristics

Colour : white, colourless, gray, pink, lilac, violet, yellow and green
Luster : vitreous
Transparency : crystals are transparent to translucent
Crystal System : monoclinic; 2/m
Crystal Habits :
include prismatic, generally flattened and elongated crystals. The termination is usually the two faces of a dome or rounded, curved and faces indisernable. Crystal faces are often pitted and rough. Some crystals of spodumene have been found in record large crystals of more than 12 meters long
Cleavage :
perfect in two direction at close to right angles and a parting direction that breaks diagonally transect one of the cleavage angles and is parallel to the typical flattening of the crystals

Fracture : splintery due to the cleavage and parting
Hardness : 6.5 - 7
Specific Gravity : approxi. 3.2 (slightly above average)
Streak : white
Other :
index of refraction is 1.66, prism faces are deeply striated lengthwise and clear colourful varieties show strong pleochroic colour intensity variation when a crystal is viewed from the top or bottom then from other directions
Associated Minerals : lepidolite, plagioclase feldspars, quartz, tourmaline and topaz
Major Occurrences :
include California, North Carolina and South Dakota, USA; Afganistan; Pakistan; Brazil and Madagascar
Best Indicators : crystal habit, striated prisms, colour, fracture and cleavage RELATED POST