Cervantite

Cervantite is an antimony oxide mineral with formula Sb³⁺Sb⁵⁺O₄ (antimony tetroxide).

Cervantite
Microscopic cervantite crystals from Slovakia (3 mm field of view)
General
Category	Oxide mineral
Formula (repeating unit)	Sb3+Sb5+O4
IMA symbol	Cvn[1]
Strunz classification	4.DE.30
Crystal system	Orthorhombic
Crystal class	Pyramidal (mm2) (same H-M symbol)
Space group	Pbn21
Unit cell	a = 5.43 Å, b = 4.81 Å, c = 11.76 Å; Z = 4
Identification
Color	Yellow to nearly white
Crystal habit	Microscopic acicular crystals; massive
Cleavage	Excellent on {001}, distinct on {100}
Fracture	Conchoidal
Mohs scale hardness	4–5
Luster	Greasy, pearly, earthy
Streak	Pale yellow to white
Diaphaneity	Semitransparent
Specific gravity	6.5
Optical properties	Biaxial
Refractive index	nα = 2.000 nγ = 2.100
Birefringence	δ = 0.100
Dispersion	relatively weak
References	[2][3][4][5]

It was first described in 1850 for an occurrence in Cervantes, Sierra de Ancares, Lugo, Galicia, Spain, and named for the locality.[4] The mineral was questioned and disapproved, but re-approved and verified in 1962 based on material from the Zajaca-Stolice district, Brasina, Serbia.[3] It occurs as a secondary alteration product of antimony bearing minerals, mainly stibnite.[3]

Cervantite and valentinite replacing stibnite from the Xikuangshan Mine of Hunan Province, China (size: 16.1 x 5.0 x 3.0 cm)