Spodumene

minerals

eucryptite

lithium

kunzite

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Formula: LiAlSi2O6
Inosilicate (chain silicate), clinopyroxene
Kunzite is a variety of spodumene
Specific gravity: 3.1 to 3.2
Hardness: 6½ to 7
Streak: White
Colour: Colourless, white, pink and lilac (kunzite), green (hiddenite), yellow, brown
Solubility: Insoluble in hydrochloric, sulphuric and nitric acid
Common impurities: Fe,Mn,Mg,Ca,Na,K,H2O
Environments:

Pegmatites

Spodumene is found almost exclusively as a primary mineral in lithium-rich pegmatites.

Localities

The Peatfold pegmatite at Glenbuchat, Strathdon, Aberdeenshire, Scotland, UK, shows a distinctly zoned structure, broadly symmetrical around a central core of bright purple mica, probably lepidolite. The spodumene lens contains striated, fractured intergrown crystals of spodumene, associated with plentiful tourmaline. This occurrence of spodumene is thought to be the first substantiated report of the mineral from Scotland. (JRS 20.30-33).

At the White Picacho District, Arizona, USA, the alteration sequence for spodumene is
spodumeneeucryptite + albitemuscovite + albitemuscovite
(AM 67: 97-113).
The zoning sequence within the pegmatite goes from spodumene + quartz to spodumene + montebrasite + quartz to montebrasite + quartz (R&M 92.2.151)

At the Emmons pegmatite, Greenwood, Oxford county, Maine, USA, spodumene crystals to 50 cm are associated with amblygonite-montebrasite, pollucite and alkali-rich beryl. The Emmons pegmatite is an example of a highly evolved boron-lithium-cesium-tantalum enriched pegmatite (R&M 94.6.515). Talc pseudomorphs after spodumene have been found here (KL p235).

Alteration

petalite to spodumene and quartz
LiAlSi4O10 ⇌ LiAlSi2O6 + 2SiO2
(DHZ 4 p274)

spodumene, quartz and Na+ to albite and Li+
LiAlSi2O6 + SiO2 + Na+ → NaAlSi3O8 + Li+
Whether spodumene breaks down into albite or into eucryptite and albite depends largely on the presence or absence of quartz (AM 67: 97-113).

spodumene and Na+ to eucryptite, albite and Li+
2LiAlSi2O6 + Na+ → LiAlSiO4 + NaAlSi3O8 + Li+
Whether spodumene breaks down into albite or into albite or into eucryptite and albite depends largely on the presence or absence of quartz (AM 67: 97-113).

spodumene, K+ and H+ to muscovite, quartz and Li+
3LiAlSi2O6 + K+ + 2H+ → KAl3Si3O10(OH)2 + 3SiO2 + 3Li+
The direct conversion of spodumene to muscovite liberates silica, but quartz is not usually present in pseudomorphs of muscovite after spodumene, and this requires an explanation (AM 67: 97-113).

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