Mineral Type - Labradorite

A plagioclase feldspar with an albite : anorthite molar ratio ranging from 30 : 70 to 50 : 50. An intermediate member of the Albite-Anorthite Series.
Originally found at Ford Harbour, Paul Island, near Nain, off the east coast of Labrador, Newfoundland and Labrador [56° 30' N, 61° 30' W].

Name

From the occurrence at Ford Harbour, Paul Island,Labrador, Canada (Nain anorthosite).

Physical Properties

Lustre: Sub-Vitreous
Colour: Pale green, blue, colourless, grey-white. Labradorescent: blue-green, golden yellow, purple, bronze colour.
Streak: White
Hardness: 6 - 6½ on Mohs scale
Cleavage: Perfect

Chemical Properties

Formula: (Ca,Na)[Al(Al,Si)Si2O8]
Elements listed: Al, Ca, Na, O, Si

Crystallography

Crystal System: Triclinic
Class (H–M): 3 2 – Trapezohedral
Space Group: P31 2 1

Synonyms

Black Moonstone, Carnatite, Labrador Feldspar, Labrador Moonstone, Mauilite, Opaline Feldspar, Radauite, and Silicite

Varieties

Lynx Eye, Oregon Sunstone, and Spectrolite

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