Hopeite

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Hopeite
Hopeite Vieille Montagne.jpg
Hopeite Belgium - Type locality
General
Category Phosphate minerals
Formula
(repeating unit)
Zn3(PO4)2·4H2O
Strunz classification 08.CA.30
Identification
Formula mass 458.17
Color Colorless, Gray white, Yellow, White, Light yellow
Crystal habit

Encrustations - Forms crust-like aggregates on matrix.

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline). Reniform - "Kidney like" in shape (e.g.. hematite).
Crystal system Orthorhombic (2/m 2/m 2/m) Space Group: P nma
Cleavage [100] Perfect, [010] Good, [001] Poor
Fracture Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.
Mohs scale hardness 3-3.5
Luster Vitreous (Glassy)
Streak white
Specific gravity 3
Optical properties Biaxial (-), a=1.572-1.574, b=1.582-1.591, g=1.59-1.592
Other characteristics non-radioactive, non-magnetic

Hopeite is a hydrated zinc phosphate with formula: Zn3(PO4)2·4H2O. It is a rare mineral used mainly as a collectors specimen.

Hopeite crystallizes in the orthorhombic system with prismatic, vitreous white to yellow crystals. It also forms druzy encrustations and reniform (kidney-shaped) masses. The related mineral parahopeite, which has the same composition but different crystal structure, is triclinic. The minerals are formed through oxidation of sphalerite by the presence of phosphate-rich solutions

It was first described in 1822 from Moresnet, Liège Province, Belgium and is named after Scottish chemist, Thomas Charles Hope (1766–1844) of Edinburgh University.

It has been found in Zambia associated with lazulite.

References[edit]

Orange-brown hopeite prisms to 3 mm on a nearly solid matrix of glassy, pastel yellow-green parahopeite crystals. Locality: Kabwe Mine (Broken Hill Mine), Kabwe, Central Province, Zambia. Broken Hill is the type locality for parahopeite.