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Spodumene

Class: Silicates
Group: Pyroxene

Varieties | Names:

A common constituent of lithium-rich granite pegmatites; in gneisses (Anthony et al., 2001—2005).
Spodumene — specimen 0454
Spodumene — specimen 0454, photo © NMNHS

Original description: d’Andrada, J. B., 1800. Kurze Angabe der Eigenschaften und Kennzeichen einiger neuen Fossilien aus Schweden und Norwegen, nebst einigen chemischen Bemerkungen über dieselben — Allgemeines Journal der Chemie 4: 30—31 [view in ‘Library’].

Type locality: Utö mines, Utö, Södermanland, Sweden.

Type material: unknown.

Etymology: from the Greek for reduced to ashes, alluding to the greyish white mass that is formed when the mineral is ignited.

Distribution: Afghanistan: Laghman; Brazil: Minas Gerais; Madagascar; Sweden; USA: from the Pala district, San Diego Co., California; at Hiddenite, Alexander Co., North Carolina; Zimbabwe (Anthony et al., 2001—2005).

Chemistry

LiAlSi2O6

Essential elements: lithium (Li), oxygen (O), aluminium (Al), silicon (Si).

Crystal data

Crystallography: monoclinic — prismatic. Crystal habit: crystals prismatic, typically flattened and striated, to 12.5 m and 54 t; common ly massive. Twinning: common on {100} (Anthony et al., 2001—2005).

Physical properties

Cleavage: good on {110}; parting on {100}, {010} (Anthony et al., 2001—2005). Fracture: uneven to conchoidal (Anthony et al., 2001—2005). Tenacity: brittle (Arem, 1987: 179). Hardness: 6—7 (Lazzarelli, 2012). Density: 3.15—3.21 g/cm3 (Lazzarelli, 2012). Luminescence: fluoresces yellow, orange, or pink under LW and SW UV (Anthony et al., 2001—2005).

Optical properties

Colour: colourless, greenish white, greyish white, yellowish green, emerald-green, yellow, pink, violet, may be bicoloured; colourless in thin section (Anthony et al., 2001—2005). Diaphaneity: transparent to translucent (Anthony et al., 2001—2005). Lustre: vitreous (Arem, 1987: 179). Refractive index: 1.657—1.681 — anisotropic [biaxial (+)] (Lazzarelli, 2012). Birefringence: 0.014—0.016. Dispersion: 0.017 (Arem, 1987: 179). Pleochroism: X = purple to green; Z = colourless (Anthony et al., 2001—2005).

Material from ‘Repository’

3 specimens: 0454 — 9.40 ct, no precise locality [Africa]; 0443 — 5.07 ct, no precise locality [Africa]; 0146 — 7.25 ct, Afghanistan.


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