Pezzottaite

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Pezzottaite
General
Category	Cyclosilicate minerals
Formula (repeating unit)	Cs(Be2Li)Al2Si6O18
IMA symbol	Pez[1]
Crystal system	Trigonal
Crystal class	Ditrigonal pyramidal (3m) (same H-M symbol)
Space group	R3c
Identification
Color	Raspberry red, orange-red, pink
Crystal habit	flattened, tabular, equant, aggregate
Cleavage	Imperfect; basal
Fracture	Conchoidal to uneven
Tenacity	brittle
Mohs scale hardness	8
Luster	Vitreous
Streak	White
Specific gravity	3.10
Optical properties	uniaxial
Refractive index	1.601 to 1.620
Birefringence	−0.008 to 0.011
Pleochroism	Moderate dichroic
References	[2][3][4]

Pezzottaite, marketed under the name raspberyl or raspberry beryl, is a mineral species first recognized by the International Mineralogical Association in September 2003. Pezzottaite is a caesium analogue of beryl, a silicate of caesium, beryllium, lithium and aluminium, with the chemical formula Cs(Be₂Li)Al₂Si₆O₁₈. Named after Italian geologist and mineralogist Federico Pezzotta, pezzottaite was first thought to be either red beryl or a new variety of beryl ("caesium beryl"); unlike actual beryl, however, pezzottaite contains lithium and crystallizes in the trigonal crystal system rather than the hexagonal system.