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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:
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
spodumene → eucryptite +
albite → muscovite +
albite → muscovite
(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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