A lithium-bearing pyroxene,
lithium aluminum silicate (LiAlSi2O6); a major lithium
ore found in pegmatites, forming clear
monoclinic system crystals or masses. It is opaque or transparent in many
hues, and the transparent lilac and green varieties are used as gems.
Hardness 6.5–7; relative density 3.2.
AND PLANETARY SCIENCE