Gwihabaite
(repeating unit)(NH4,K)NO3 IMA symbol Gwi[1] Strunz classification 5.NA.15 Dana classification 18.01.03.01 Crystal system Orthorhombic Crystal class Dipyramidal Space group Pmna (No. 62) Unit cell a=7.075Å, b=7.647Å, c=5.779Å, Z=4 Identification Formula mass 85.31 Colour White, colourless Crystal habit Acicular, Efflorescences Cleavage None Mohs scale hardness 5 Luster Vitreous Streak White Diaphaneity Transparent Density 1.77 Birefringence 0.141 2V angle 87◦ Dispersion None Solubility Soluble in H2O , deliquescent
Gwihabaite is a rare ammonium potassium nitrate mineral (NH4,K)(NO3). It is orthorhombic in form, colorless with a vitreous luster. It has a Mohs hardness of 5 and a specific gravity of 1.77. It is deliquescent and water-soluble. The mineral is also known as nitrammite. It was first described in 1996 for an occurrence in Gcwihaba Caves (Drotsky's Cavern, type locality), Maun, North-West District, Botswana. The spelling of the name was simplified, omitting the "c", which represents the "click" sound used by the San people. It occurs as incrustations and efflorescences on cave surfaces formed by bacterial action on bat guano.[2][3]
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