Hydrozincite

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

Hydrozincite
Hydrozincite-Smithsonite-210865.jpg
General
CategoryCarbonate mineral
Formula
(repeating unit)
Zn5(CO3)2(OH)6
Strunz classification5.BA.15
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupC2/m
Unit cella = 13.58 Å, b = 6.28 Å,
c = 5.41 Å; β = 95.51°, Z = 2
Identification
ColorWhite to grey, stained pale pink, or pale yellow or brown; colourless in transmitted light.
Crystal habitLathlike or bladed crystals uncommon, in fibrous, stalactitic, reniform, pisolitic aggregates; also earthy, chalky, massive
TwinningContact twinning on {100}
CleavagePerfect on {100}
FractureIrregular/uneven
TenacityVery brittle
Mohs scale hardness2 - 2+12
LusterSilky, pearly, dull, earthy
StreakWhite
DiaphaneityTransparent, translucent
Specific gravity3.5 - 4
Optical propertiesBiaxial (-)
Refractive indexnα = 1.630 nβ = 1.642 nγ = 1.750
Birefringenceδ = 0.120
2V angleMeasured: 40° , calculated: 40°
Dispersionrelatively strong
Ultraviolet fluorescenceFluoresces pale blue to lilac under UV
SolubilityReadily soluble in acids.
References[1][2][3]

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]

ReferencesEdit