Gemmology
English | Български
Where am I? > Home > Classification > Smithsonite


Quick navigation selector

Smithsonite

Class: Carbonates (Nitrates)
Group: Calcite

Varieties | Names:

A secondary mineral formed in the oxidised zone of zinc-bearing deposits and replacing adjacent carbonate rocks (Anthony et al., 2001—2005).

Original description: Beudant, F. S., 1832. Smithsonite, Zinc carbonaté — Traité Élémentaire de Minéralogie, Paris: 354—357 [view in ‘Library’].

Type locality: United Kingdom of Great Britain and Northern Ireland.

Type material: unknown.

Etymology: in honour of James Lewis Smithson, British chemist and mineralogist, whose bequest founded the Smithsonian Institution, Washington, DC.

Distribution: many localities: Austria; Belgium; France; Germany; Greece; Italy: Sardinia; Mexico: Chihuahua; Namibia: Tsumeb; Poland; USA; Zambia (Anthony et al., 2001—2005).

Chemistry

ZnCO3

Essential elements: carbon (C), oxygen (O), zinc (Zn).

Crystal data

Crystallography: trigonal — hexagonal scalenohedral. Crystal habit: uncommon as crystals, to 10 cm, rhombohedral and scalenohedral; typically botryoidal, reniform; earthy, friable, granular to porous or massive (Anthony et al., 2001—2005).

Physical properties

Cleavage: on {1011}, nearly perfect (Anthony et al., 2001—2005). Fracture: uneven to conchoidal (Anthony et al., 2001—2005). Tenacity: brittle (Arem, 1987: 174). Hardness: 4—4.5 (Arem, 1987: 174). Density: 4.3—4.45 g/cm3 (Arem, 1987: 174). Luminescence: may fluoresce pale green or pale blue under UV (Anthony et al., 2001—2005).

Optical properties

Colour: white, pale grey, dark grey, pale brown, brown, more rarely pale shades of red, pink, orange, yellow, green, apple-green, emerald-green, blue, bluish grey; colourless to faintly tinted in transmitted light (Anthony et al., 2001—2005). Diaphaneity: transparent to translucent (Anthony et al., 2001—2005). Lustre: vitreous, pearly (Anthony et al., 2001—2005). Refractive index: 1.62—1.85 — anisotropic [uniaxial (-)] (Lazzarelli, 2012). Birefringence: 0.227. Dispersion: 0.037 (Arem, 1987: 174). Pleochroism: none.

Material from ‘Repository’

4 specimens: 0039 — 1.28 ct, Mexico; 0297 — 2.27 ct, Mexico; 0298 — 2.23 ct, Mexico; 0543 — 0.73 ct, Mexico.


Gallery view