Chlorocalcite

Chlorocalcite is a rare potassium calcium chloride evaporite mineral with formula: KCaCl₃. It is found in active volcanic fumaroles.

Chlorocalcite
General
Category	Halide mineral
Formula	KCaCl3
IMA symbol	Ccal[1]
Strunz classification	3.AA.40
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m)
Space group	Pnma (from synthetic crystals)
Unit cell	a = 7.35 Å, b = 10.44 Å, c = 7.25 Å; Z = 4
Identification
Formula mass	185.54 g/mol
Color	White, tinged violet
Crystal habit	Prismatic or tabular cube-like crystals, pseudo cubic
Cleavage	Perfect on {001}, good on {010} and {100}
Mohs scale hardness	2.5-3
Diaphaneity	Transparent to semi-transparent
Density	2.16 calculated
Optical properties	Biaxial (–)
Refractive index	~1.52
Birefringence	weak
Solubility	In water
Other characteristics	Deliquescent
References	[2][3][4][5]

It was first described in 1872 for an occurrence on Mount Vesuvius and given the name for its calcium content previous to discovering that it also contained potassium.^[3][4] It has also been reported from the Desdemona Mine, Peine, Lower Saxony, Germany.^[3]