Jadeite

Class: Silicates
Group: Pyroxene

In metamorphic rocks; a component of eclogite (Anthony et al., 2001—2005).

Original description: Damour, A. A., 1863. Notice et analyse sur le jade vert. Réunion de cette matière minérale à la famille des Wernerites — Comptes Rendus Hebdomadaires des Séances de l’Académie des Sciences 56: 861—865 [view in ‘Library’].

Type locality: Myanmar.

Type material: unknown.

Etymology: from jade, a material commonly containing jadeite.

Distribution: Guatemala: in the Motagua Valley, near the Sierra de las Minas; Japan; Myanmar: Kachin; Russia: around Lake Baikal, Siberia; USA: California, San Benito (Anthony et al., 2001—2005).

Chemistry

NaAlSi2O6

Essential elements: oxygen (O), sodium (Na), aluminium (Al), silicon (Si).

Crystal data

Crystallography: monoclinic — prismatic. Crystal habit: crystals rare, prismatic with {110}, {111}, and {100} as dominant forms; commonly massive, or fibrous, granular, compact. Twinning: single and lamellar on {100} and {001} (Anthony et al., 2001—2005).

Physical properties

Cleavage: none (Arem, 1987: 117). Fracture: splintery (Arem, 1987: 117). Tenacity: very tough (Arem, 1987: 117). Hardness: 6.5—7 (Arem, 1987: 117). Density: 3.28—3.38 g/cm3 (Lazzarelli, 2012). Luminescence: none.

Optical properties

Colour: apple-green, emerald-green, bluish green, greenish white, white, may show green spots, rarely blue or violet; colourless in thin section (Anthony et al., 2001—2005). Diaphaneity: translucent (Anthony et al., 2001—2005). Lustre: vitreous (Arem, 1987: 117). Refractive index: 1.652—1.688 — anisotropic [biaxial (+)] (Lazzarelli, 2012). Birefringence: 0.012—0.02. Dispersion: none. Pleochroism: none (Arem, 1987: 117).

Material from ‘Repository’

2 specimens: 0200 — 3.01 ct, Myanmar; 0203 — 3.40 ct, Myanmar.

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