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Norbergite
Current inventory:  0 gems
 

  
Norbergite gets its name from the locality where it was discovered; Norberg, Sweden.

Discovered in 1926;   IMA status: Valid (pre-IMA; Grandfathered).

Chemistry

Chemical Formula:

Mg₃(SiO₄)(F,OH)₂  

Magnesium Silicate Fluoride Hydroxide

Molecular Weight:

202.00 gm

Composition: 

Classification

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/B.04-10

Nickel-Strunz 10th Ed. ID:

9.AF.40

9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination

Related to:

Humite Group.

Synonyms:

Grothine

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

Crystals rare, to 2.5 cm, thick tabular, typically rounded and highly modified; granular.

Twinning:

None

Physical Properties

Cleavage:

[???] Distinct

Fracture:

Irregular/Uneven to Sub-Conchoidal

Tenacity:

Brittle

Moh's Hardness:

6.0 - 6.5

Density:

3.177 (g/cm³)

Luminescence:

May fluoresce tan to canary-yellow under SW UV.

Radioactivity:

Not Radioactive

Optical Properties

Color:

Tan, Yellow, Yellow-Orange, Orange-Brown, Pink with Purplish tint, White; pale Yellow to Colorless in thin section

Transparency:

Transparent to Translucent

Luster:

Vitreous to Resinous

Refractive Index:

1.563 - 1.593  Biaxial ( + )

Birefringence:

0.0270

Dispersion:

Slight to Strong; r > v

Pleochroism:

X = pale yellow; Y = very pale yellow; Z = colorless

Occurances

Geological Setting:

In contact metamorphic zones in limestones and dolostones into which plutonic rocks or pegmatites have introduced fluorine.

Common Associations:

Calcite, Cuspidine, Dolomite, Fluoborite, Fluorite, Forsterite, Grossular, Ludwigite, Monticellite, Phlogopite, Tremolite, Wollastonite

Common Impurities:

Ti, Al, Fe, Mn, Zn, Ca, H₂O

Type Locality:

Östanmoss mine, Norberg, Västmanland, Sweden

Year Discovered:

1926

View mineral photos:

Norbergite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Norbergite is a rare member of the Humite Group of minerals that includes Chondrodite, Clinohumite, and Norbergite. It is one of several rare minerals that have been found at the famous mines at Franklin, New Jersey, USA. It is also one of the many fluorescent minerals found there. It will glow tan to canary-yellow under SW UV. Norbergite rarely forms as transparent crystals but mostly as opaque crystals or granular masses. Therefore, Norbergite is only suitable for cabochons.

There are only a few locations for finding Norbergite, at the Type Locality of Östanmoss mine, Norberg, Västmanland, Sweden; Mogok, Sagaing District, Mandalay Division, Burma (Myanmar); San Vito quarry, San Vito, Ercolano, Monte Somma, Somma-Vesuvius Complex, Naples Province, Campania, Italy; Near Loch Ness, Inverness-shire, Scotland, in the USA at Franklin, Franklin Mining District, Sussex County, New Jersey; Limecrest Quarry, Sparta Township, Sussex Co., New Jersey.
 

  
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