Cafetite

Cafetite
Yellow cafetite crystals with green lizardite and calcite
General
Category	oxide mineral
Formula	(Ca,Mg)(Fe,Al) 2Ti 4O 12·4(H 2O)
IMA symbol	Cft1
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 = 82
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	2345

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

It was first described in 1959 for an occurrence in the Afrikanda Massif, Afrikanda, Kola Peninsula, Murmanskaja Oblast, Northern Region, Russia.⁴³ 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