Class: Silicates
Group: Aenigmatite
Original description: ‘Saphirin’ Stromeyer, F., 1819. 2. Saphirin von Fiskenaes oder Kikertarsoeitsiak — Göttingische gelehrte Anzeigen 3: 1994—1995 [
view in ‘Library’].
Type locality: Fiskenaes old harbour, Fiskenaes, Nuuk, Sermersooq, Greenland.
Type material: unknown.
Etymology: for its sapphire-like colour.
Distribution: Canada: at Wilson Lake, Labrador; Germany: from Waldheim, Saxony; Greenland: Fiskenaes; Italy: Piedmont; Madagascar; South Africa: Transvaal; Tanzania (
Anthony et al., 2001—2005).
Chemistry
(Al,Mg)8(Al,Si)6O20
Essential elements: oxygen (O), magnesium (Mg), aluminium (Al), silicon (Si).
Crystal data
Crystallography: monoclinic — prismatic or triclinic — pinacoidal.
Crystal habit: crystals indistinct, tabular on {010}, to 3 cm; commonly as disseminated grains or aggregates.
Twinning: repeated on {010}; uncommon (
Anthony et al., 2001—2005).
Optical properties
Colour: light to dark blue or green, white, grey, pale red, yellow; in thin section, colourless to blue or pink (
Anthony et al., 2001—2005).
Diaphaneity: transparent to translucent (
Anthony et al., 2001—2005).
Lustre: vitreous (
Arem, 1987: 165).
Refractive index: 1.701—1.724 — anisotropic [biaxial (-)] (
Lazzarelli, 2012).
Birefringence: 0.005—0.007.
Dispersion: 0.019.
Pleochroism: X = colourless, pale reddish, yellowish green, pale yellow; Y = sky-blue, bluish green; Z = blue, dark blue (
Anthony et al., 2001—2005).
Material from ‘Repository’
