Hydrozincite

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Hydrozincite
Hydrocynkit, Kopalnia Ojuela, Mapimi, Durango, Meksyk.jpg
Hydrozincite
General
Category Carbonate mineral
Formula
(repeating unit)
Zn5(CO3)2(OH)6
Strunz classification 05.BA.15
Crystal symmetry Monoclinic prismatic H–M Symbol 2/m
Unit cell a = 13.58 Å, b = 6.28 Å,
c = 5.41 Å; β = 95.51°, Z = 2
Identification
Color White to grey, stained pale pink, or pale yellow or brown; colourless in transmitted light.
Crystal habit Lathlike or bladed crystals uncommon, in fibrous, stalactitic, reniform, pisolitic aggregates; also earthy, chalky, massive
Crystal system Monoclinic
Twinning Contact twinning on {100}
Cleavage Perfect on {100}
Fracture Irregular/uneven
Tenacity Very brittle
Mohs scale hardness 2 - 2½
Luster Silky, pearly, dull, earthy
Streak White
Diaphaneity Transparent, translucent
Specific gravity 3.5 - 4
Optical properties Biaxial (-)
Refractive index nα = 1.630 nβ = 1.642 nγ = 1.750
Birefringence δ = 0.120
2V angle Measured: 40° , calculated: 40°
Dispersion relatively strong
Ultraviolet fluorescence Fluoresces pale blue to lilac under UV
Solubility Readily soluble in acids.
References [1][2][3]

Hydrozincite, also known as zinc bloom, is a white carbonate mineral consisting of Zn5(CO3)2(OH)6. It is usually found in massive rather than crystalline form.

It occurs as an oxidation product of zinc ores and as post mine incrustations. It occurs associated with smithsonite, hemimorphite, willemite, cerussite, aurichalcite, calcite and limonite.[1]

It was first described in 1853 for an occurrence in Bad Bleiberg, Carinthia, Austria and named for its chemical content.[2]

References[edit]