Enstatite
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Enstatite is a mineral; the magnesium endmember of the pyroxene silicate mineral series enstatite – ferrosilite. The magnesium rich members of the solid solution series are common rock-forming minerals found in igneous and metamorphic rocks. Wikipedia
Cleavage: Good/distinct on
Mineral chemical formula: Mg2Si2O6
2V angle: 55–90°
Birefringence: δ = 0.009–0.011
Color: White, grey, green, yellow or brown - colorless in thin section
Crystal class: Dipyramidal (mmm); H-M symbol: (2/m 2/m 2/m)
Crystal habit: Prismatic crystals, commonly lamellar, fibrous, or massive