Norbergite
Current inventory:  1 gem
 

  
Norbergite is named 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:

Magnesium

36.10 %

Mg

59.86 %

MgO

Silicon

13.90 %

Si

29.74 %

SiO₂

Hydrogen

0.25 %

H

2.23 %

H₂O

Oxygen

35.64 %

O

Fluorine

14.11 %

F

14.11 %

F

-

-   %

F

-5.94 %

-O=F₂

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

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.

Members of Group:

Humite Group: Alleghanyite, Chegemite, Chondrodite, Clinohumite, Edgrewite, Humite, Hydroxylchondrodite, Hydroxylclinohumite, Jerrygibbsite, Kumtyubeite, Leucophoenicite, Manganhumite, Norbergite, Reinhardbraunsite, Ribbeite, Sonolite

Varieties:

None

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-yellow to canary-yellow under SW UV light.

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, Humite 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. It is often found associated with other fluorescing minerals such as red fluorescing Calcite and blue fluorescing Diopside. The combination of different fluorescing colors can be quite attractive. Norbergite rarely forms as transparent crystals but mostly as tiny translucent to 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.
 

  
Norbergite gems for sale: