Cafetite

Cafetite is a rare titanium oxide mineral with formula (Ca,Mg)(Fe,Al)
₂Ti
₄O
₁₂·4(H
₂O). It is named for its composition, Ca-Fe-Ti.[5]

Cafetite
Yellow cafetite crystals with green lizardite and calcite
General
Category	oxide mineral
Formula (repeating unit)	(Ca,Mg)(Fe,Al) 2Ti 4O 12·4(H 2O)
IMA symbol	Cft[1]
Strunz classification	4.FL.75
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/n
Unit cell	a = 4.944 Å, b = 12.109 Å, c = 15.911 Å; β= 98.93°; Z = 8[2]
Identification
Color	Pale yellow to colorless
Crystal habit	Elongated columnar to acicular crystals, fibrous aggregates, pseudo-orthorhombic
Cleavage	Prismatic
Tenacity	Brittle
Mohs scale hardness	4-5
Luster	Adamantine
Streak	White
Diaphaneity	Semitransparent
Specific gravity	3.28
Optical properties	Biaxial (–), 2V=58°, Dispersion very strong, r > v
Refractive index	nα = 1.95, nβ = 2.08, nγ = 2.11
Birefringence	δ = 0.16
Pleochroism	none
2V angle	Measured: 38°
References	[2][3][4][5]

It was first described in 1959 for an occurrence in the Afrikanda Massif, Afrikanda, Kola Peninsula, Murmanskaja Oblast, Northern Region, Russia.[4][3] It is also reported from the Khibiny and Kovdor massifs of the Kola Peninsula and from Meagher County, Montana, US.[4]

It occurs in pegmatites in a pyroxenite intrusion as crystals in miarolitic cavities. It occurs associated with ilmenite, titaniferous magnetite, titanite, anatase, perovskite, baddeleyite, phlogopite, clinochlore and kassite.[3]