Diaspore /ˈdaɪəspɔːr/ , also known as diasporite, empholite, kayserite, or tanatarite, is an aluminium oxide hydroxide mineral, α-AlO(OH), crystallizing in the orthorhombic system and isomorphous. 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—like mica , and gypsum — by its greater hardness of 6.5 - 7. The specific gravity is 3.4. When heated before the blowpipe it decrepitates violently, breaking up into white pearly scales.
The mineral occurs as an alteration product of corundum or emery and other crystalline rocks. Well-developed crystals are found in the emery deposits of the Urals , and in kaolin. If obtainable in large quantity, it would be of economic importance as a source of aluminium
Diaspore, along with gibbsite , is a major component of the aluminium ore
It was first described in 1801 for an occurrence in Mramorsk Zavod, Sverdlovskaya Oblast , Russia is from the Greek for διασπείρειν, to scatter, in allusion to its decrepitation on heating.
Csarite, ottomanite, and zultanite are trade names for gem-quality diaspore (also known as Turkish diaspore) from the İlbir Mountains