Diaspore

Aluminium hydroxide oxide mineral

Diaspore – also called diasporite, empholite, kayserite, or tanatarite – is an aluminium hydroxide oxide mineral, α-AlO(OH), crystallizing in the orthorhombic system and isomorphous with goethite. It occurs sometimes as flattened crystals, but usually as lamellar or scaly masses, the flattened surface being a direction of perfect cleavage on which the lustre is markedly pearly in character. It is colorless or greyish-white, yellowish, sometimes violet in color, and varies from translucent to transparent. It may be readily distinguished from other colorless transparent minerals with a perfect cleavage and pearly luster by its greater hardness of 6.5–7. Its specific gravity is 3.4. When heated before the blowpipe, it decrepitates violently, breaking up into white pearly scales.

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