Leucite is a gray or white feldspar mineral – a potassium
aluminum silicate (KAl(SiO3)2). Unstable at high pressures,
it has a restricted occurrence. Leucite can be found in potassium-rich lava flows
and volcanic plugs. It forms crystals having 24 equal faces. Hardness 5.5–6, relative density 2.5.
|A leucite crystal and crystal structure
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