Carobbiite

Carobbiite, chemical formula KF (potassium fluoride), is a rare, soft (Mohs 2 - 2.5), colourless cubic mineral.^[2] It is found at Monte Somma, Somma-Vesuvius Complex, Province of Naples, Campania, Italy. It was discovered in 1956 by Italian geologist Guido Carobbi (1900–1983).^[3] It has also been reported from Hokkaido, Japan.^[4]

Carobbiite
Carobbiite
General
Category	Minerals
Formula	KF
IMA symbol	Crb[1]
Strunz classification	3.AA.20
Dana classification	9.1.1.4
Crystal system	Isometric - Hexoctahedral
Crystal class	m3m (4/m 3 2/m) - Hexoctahedral
Space group	Cubic
Unit cell	152.27 ų
Identification
Formula mass	58.10 gm
Colour	Colorless
Cleavage	Distinct/Good
Mohs scale hardness	2-2.5
Luster	Vitreous (Glassy)
Streak	White
Diaphaneity	Transparent
Specific gravity	2.505
Density	2.524
Optical properties	Isotropic, n=1.362.