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Vesuvianite

Class: Silicates
Group: Vesuvianite

In skarns formed during contact or regional metamorphism of limestones; in mafic and ultramafic rocks, and serpentinites; uncommon in alkalic igneous rocks (Anthony et al., 2001—2005).

Original description: ‘Vesuvian’ Klaproth, M. H., 1795. Vesuvian, hellbrauner — Beiträge zur Chemischen Kenntniss der Mineralkörper 1: 34—35 [view in ‘Library’].

Type locality: Monte Somma, Somma-Vesuvius Complex, Naples Province, Campania, Italy.

Type material: Technische Universität Bergakademie, Freiberg, Germany, 23278 (Anthony et al., 2001—2005).

Etymology: re-named ‘vesuvian’ after its type locality, Mount Vesuvius, Campania, Italy.

Distribution: Canada: Asbestos and Mont Saint-Hilaire, Quebec; Italy: at Monte Somma and Vesuvius, Campania; Mexico: Chihuahua; Norway: Arendal; Russia: near Zlatoust, Urals; Switzerland: near Zermatt, Valais; USA: California (Anthony et al., 2001—2005).

Chemistry

Ca10Mg2Al4(SiO4)5(Si2O7)2(OH)4

Essential elements: hydrogen (H), oxygen (O), magnesium (Mg), aluminium (Al), silicon (Si), calcium (Ca).

Crystal data

Crystallography: tetragonal — dipyramidal. Crystal habit: commonly as short pyramidal to long prismatic crystals, to 15 cm, morphologically complex, with up to 30 forms reported on one crystal; columnar, granular, massive (Anthony et al., 2001—2005).

Physical properties

Cleavage: {110}, poor; {100} and {001}, very poor (Anthony et al., 2001—2005). Fracture: subconchoidal to irregular (Anthony et al., 2001—2005). Tenacity: brittle (Anthony et al., 2001—2005). Hardness: 6.5 (Lazzarelli, 2012). Density: 3.25—3.5 g/cm3 (Lazzarelli, 2012). Luminescence: none (Arem, 1987: 115).

Optical properties

Colour: yellow, green, brown; colourless to white, blue, violet, bluish green, pink, red, black, commonly zoned; in transmitted light, colourless to light yellow, green, brown (Anthony et al., 2001—2005). Diaphaneity: transparent to translucent (Anthony et al., 2001—2005). Lustre: vitreous to resinous (Arem, 1987: 115). Refractive index: 1.7—1.725 — anisotropic [uniaxial (+/-)] (Lazzarelli, 2012). Birefringence: 0.002—0.012. Dispersion: 0.019—0.025 (Arem, 1987: 115). Pleochroism: weak; O = colourless to yellowish; E = yellowish, greenish, brownish (Anthony et al., 2001—2005).

Material from ‘Repository’

1 specimen: 0486 — 1.45 ct, Tanzania.


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