Hydrozincite - Reference.org

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Category Carbonate mineral

Formula(repeating unit) Zn5(CO3)2(OH)6

Strunz classification 5.BA.15

Crystal system Monoclinic

Crystal class Prismatic (2/m)
(same H-M symbol)

Space group C2/m

Unit cell a = 13.58 Å, b = 6.28 Å,
c = 5.41 Å; β = 95.51°, Z = 2

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

Twinning Contact twinning on {100}

Cleavage Perfect on {100}

Fracture Irregular/uneven

Tenacity Very brittle

Mohs scale hardness 2 - 2+1⁄2

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.

Additional information

Hydrozincite

White carbonate mineral

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.

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.

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