Changoite

Changoite is a rare zinc sulfate mineral with the formula Na₂Zn(SO₄)₂·4H₂O.^[5][3] Chagoite was discovered in the San Francisco Mine near Sierra Gorda, Antofagasta, Chile.^[4] The mineral is a zinc-analogue of blödite, cobaltoblödite, manganoblödite and nickelblödite - other representatives of the blödite group.^[5] In terms of chemistry changoite is somewhat similar to gordaite.^[6] The mineral's name comes from the Chango people, a group of early inhabitants of northern Chile.^[4]

Changoite
Yellowish crystals of changoite associated to hexagonal colorless caracolite in an aesthetic combination.
General
Category	Sulfate mineral
Formula	Na2Zn(SO4)2·4H2O
IMA symbol	Cgo[1]
Strunz classification	7.CC.50 (10 ed) 6/C.18-25 (8 ed)
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/a
Unit cell	a = 11.08, b = 8.25, c = 5.53 [Å], β = 100.18° (approximated); Z = 2
Identification
Color	Colorless
Crystal habit	Anhedral crystals, in small veins
Mohs scale hardness	2-3
Luster	Vitreous
Streak	White
Diaphaneity	Transparent
Specific gravity	2.50 (measured)
Optical properties	Biaxal (-)
Refractive index	nα=1.51, nβ=1.51, nγ=1.52 (approximated)
2V angle	83° (calculated)
References	[2][3][4][5]

Traces of magnesium and calcium in changoite are negligible.^[4]

Minerals associating with changoite are gypsum, zinc-bearing paratacamite, and thénardite.^[3]