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Class: Phosphates, arsenates, vanadates
Group: Turquoise

A secondary mineral occurring in hydrothermal porphyry copper deposits (Anthony et al., 2001—2005). One of the oldest gemstones; used by Ancient Egypt rulers.
Turquoise — specimen 0602
Turquoise — specimen 0602, photo © NMNHS

Original description: unknown [prehistoric].

Type locality: unknown [prehistoric].

Type material: unknown.

Etymology: named in antiquity from French ‘turquoise’ meaning ‘Turkish’.

Distribution: Belgium; Brazil; Chile; China; Congo: Katanga Province; Iran; USA: Arizona (Anthony et al., 2001—2005).



Essential elements: hydrogen (H), oxygen (O), aluminium (Al), phosphorus (P), iron (Fe), copper (Cu).

Crystal data

Crystallography: triclinic — pinacoidal. Crystal habit: rare pinacoidal crystals, {010}, {110}, {001}, to 3 mm; fine granular to cryptocrystalline, crusts, veinlets, massive (Anthony et al., 2001—2005).

Physical properties

Cleavage: none. Fracture: conchoidal to smooth (Anthony et al., 2001—2005). Tenacity: no data. Hardness: 5—6 (Arem, 1987: 194). Density: 2.3—2.9 g/cm3 (Lazzarelli, 2012). Luminescence: none.

Optical properties

Colour: sky-blue, bluish green, apple-green, greenish grey (Anthony et al., 2001—2005). Diaphaneity: transparent in crystals; translucent to opaque if massive (Anthony et al., 2001—2005). Lustre: vitreous in crystals; dull to waxy if massive (Anthony et al., 2001—2005). Refractive index: 1.61—1.65 — anisotropic [biaxial (+)] (Arem, 1987: 194). Birefringence: 0.04. Dispersion: none. Pleochroism: none.

Material from ‘Repository’

2 specimens: 0601 — 0.66 ct, USA; 0602 — 0.68 ct, USA.

Gallery view