Kassite (mineral)

Kassite is a rare mineral whose chemical formula is CaTi₂O₄(OH)₂. It crystallizes in the orthorhombic crystal system and forms radiating rosettes and pseudo-hexagonal tabular crystals which are commonly twinned. Kassite crystals are brownish pink to pale yellow in color, are translucent, and have an adamantine luster. Cleavage is distinctly visible, and the crystals are very brittle.

Kassite
Light yellow kassite's spherules with orange-yellow tabular cafetite in lizardite matrix. Base 2 mm. Locality: Val di Serra Quarry, Pilcante, Ala, Lagarina Valley, Trento Province, Trentino-Alto Adige (Trentino-Südtirol), Italy
General
Category	Hydroxide mineral
Formula (repeating unit)	CaTi2O4(OH)2
Strunz classification	4.DH.10
Dana classification	08.03.09
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/a
Identification
Formula mass	235.09 g/mol
Color	Brown red, colorless, light yellow
Crystal habit	Pseudo hexagonal
Twinning	Common, on {101} and {181}.
Cleavage	{010} Perfect, {101} Indistinct
Fracture	Brittle
Tenacity	Very brittle
Mohs scale hardness	5
Luster	Adamantine
Streak	White
Specific gravity	3.42
Density	3.42
Optical properties	Biaxial (–), 2V=58°, dispersion very strong, r > v
Refractive index	nα = 1.95, nβ = 2.13, nγ = 2.21
Birefringence	δ = 0.26
Pleochroism	none
Other characteristics	Not radioactive
References	[1][2]

It was first described in 1965 in the Afrikanda pyroxenite massif, a formation on Russia's Kola Peninsula and was named for Nikolai Grigorievich Kassin (1885–1949), a prominent Russian geologist. It occurs as miarolytic cavity fillings of alkalic pegmatites in the Kola occurrence and in nepheline syenite in the Magnet Cove igneous complex of Arkansas, US. Its mineral association includes cafetite (which with it is also polymorphous), perovskite, titanite, rutile and ilmenite.