Norbergite

Norbergite, Calcite Locality: Oakssaung Hill, Mogok, Sagaing District, Mandalay Division, Burma (Myanmar) (Locality at mindat.org) Size: 4.2 x 3.3 x 2.3 cm. © Rob Lavinsky

Chemical Formula: Mg3(SiO4)(F,OH)2
Locality: Ostanmosoa iron mine, Norberg, Vastmanland, Sweden.
Name Origin: Named after its locality.

Norbergite is a nesosilicate mineral with formula Mg3(SiO4)(F,OH)2. It is a member of the humite group.

It was first described in 1926 for an occurrence in the Ostanmosoa iron mine in Norberg, Västmanland, Sweden, for which it is named. It occurs in contact metamorphic zones in carbonate rocks intruded by plutonic rocks or pegmatites supplying the fluorine. Associated minerals include dolomite, calcite, tremolite, grossular, wollastonite, forsterite, monticellite, cuspidine, fluoborite, ludwigite, fluorite and phlogopite.

History

Discovery date : 1926
Town of Origin : NORBERG
Country of Origin : SUEDE

Optical properties

Optical and misc. Properties: Transparent – Translucide – fluorescent
Refractive Index: from 1,56 to 1,59
Axial angle 2V: 44-50°

Physical Properties

Cleavage: Distinct
Color:     White, Yellow, Brown, Red.
Density: 3.1 – 3.2, Average = 3.15
Diaphaneity: Transparent to translucent
Fracture: Sub Conchoidal – Fractures developed in brittle materials characterized by semi-curving surfaces.
Hardness: 6-6.5 – Orthoclase-Pyrite
Luminescence: Fluorescent, Short UV=bright yellow.
Luster: Vitreous – Resinous
Streak: white

Photo:

Norbergite, Calcite Locality: Oakssaung Hill, Mogok, Sagaing District, Mandalay Division, Burma (Myanmar) (Locality at mindat.org) Size: 4.2 x 3.3 x 2.3 cm. © Rob Lavinsky
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