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Class: Phosphates, arsenates, vanadates
Group: Amblygonite

An uncommon accessory mineral in zoned granite pegmatites; in high-temperature tin veins (Anthony et al., 2001—2005). Faceted specimens are relatively rare.

Original description: ‘Amblygonit’ Breithaupt, J. F. A., 1818. Gattung B. Amblygonit — Handbuch der Mineralogie von C. A. S. Hoffmann, Craz und Gerlach, Freiberg 4: 159—161 [view in ‘Library’].

Type locality: Chursdorf, Penig, Chemnitz, Saxony, Germany.

Type material: Technische Universität Bergakademie, Freiberg, Germany, 20336 (Anthony et al., 2001—2005).

Etymology: derived from the Greek words αμβλύς (amvlys) ‘blunt’ and γωνία (gonia) ‘angle’, referring to the fact that its cleavage angle slightly differs from 90°, distinguishing it from scapolite for which it was originally mistaken.

Distribution: Brazil; Canada: Manitoba, Bernic Lake; Germany: Saxony, Chemnitz, Penig, Chursdorf; Mozambique: Zambezia, Alto Ligonha district; Namibia: near Karibib; USA: Maine, Oxford Co., at Hebron (Anthony et al., 2001—2005).



Essential elements: hydrogen (H), lithium (Li), oxygen (O), fluorine (F), sodium (Na), aluminium (Al), phosphorus (P).

Crystal data

Crystallography: triclinic — pinacoidal. Crystal habit: crude crystals, typically equant with complex form development, to 1.5 m; massive. Twinning: on several laws, with microscopic polysynthetic twinning common (Anthony et al., 2001—2005).

Physical properties

Cleavage: on {100}, perfect; on {110}, good; on {011}, distinct; on {001} imperfect (Anthony et al., 2001—2005). Fracture: uneven to subconchoidal (Anthony et al., 2001—2005). Tenacity: brittle (Anthony et al., 2001—2005). Hardness: 6 (Lazzarelli, 2012). Density: 2.98—3.10 g/cm3 (Lazzarelli, 2012). Luminescence: none.

Optical properties

Colour: milk-white, pale yellow, beige, salmon-pink, pale green, pale blue, grey, may be colourless; colourless in transmitted light (Anthony et al., 2001—2005). Diaphaneity: transparent to translucent (Anthony et al., 2001—2005). Lustre: vitreous to greasy (Anthony et al., 2001—2005). Refractive index: 1.578—1.646 — anisotropic [biaxial (+/-)] (Lazzarelli, 2012). Birefringence: 0.02—0.03. Dispersion: 0.015 (low). Pleochroism: none (Arem, 1987: 40).

Material from ‘Repository’

2 specimens: 0479 — 0.95 ct, Brazil; 0435 — 0.23 ct, Brazil.

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