Nuummite  (variety of Amphibole)
Current inventory:  1 gem
 

  
The name Nuummite, which means "derived from Nuuk" in Greenlandic, was given to the rock type which was found near Nuuk, Vestgronland, Greenland in 1982, by the town council of Nuuk.

Discovered in 1982;   IMA status: Not Valid (trade name)

Information below is for Anthophyllite, the main constituent of Nuummite.

Chemistry

Chemical Formula:

(Mg₂)(Mg₅)Si₈O₂₂(OH)₂

Magnesium Silicate Hydroxide

Molecular Weight:

780.82 gm

Composition:

Magnesium

21.79 %

Mg

36.13 %

MgO

Silicon

28.78 %

Si

61.56 %

SiO₂

Hydrogen

0.26 %

H

2.31 %

H₂O

Oxygen

49.18 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/F.12-60

Nickel-Strunz 10th Ed. ID:

9.DE.05

9 : SILICATES (Germanates)
D : Inosilicates
E : Inosilicates with 2-periodic double chains, Si₄O₁₁; Clinoamphiboles

Related to:

Amphibole Group. Mg-Fe-Mn-Li Ortho-Amphibole Subgroup. Anthophyllite - Magnesio-Anthophyllite Series. Anthophyllite - Ferro-Anthophyllite Series. Anthophyllite - Gerdite Series.

Members of Group:

Amphibole Group: Calcic Clino-Amphibole Subgroup, Mg-Fe-Mn-Li Ortho-Amphibole Subgroup, Mg-Mn-Fe-Li Clino-Amphibole Subgroup, Sodic Clino-Amphibole Subgroup

Members of Sub-Group:

Mg-Fe-Mn-Li Ortho-Amphibole Subgroup: Anthophyllite, Ferro-anthophyllite, Ferrogedrite, Ferrohomquistite, Gedrite, Holmquistite, Protoferro-anthophyllite, Protomangano-ferro-anthophyllite, Sodicanthophyllite, Sodic-ferro-anthophyllite, Sodic-ferrogedrite, and Sodicgedrite.

Varieties:

Jenakite, Kupfferite (of Koksarov), Sahara Nuummite

Synonyms:

Nuummite: Nuumit, Nuumite, Nuummit.

Anthophyllite: Anthogrammite, Anthophylline, Antofillite, Gray Asbestos, Kupferite, Magnesio-Anthophyllite.

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

Crystals rare, to 25 cm; as bladed aggregates of unterminated prismatic crystals. Commonly lamellar or fibrous, asbestiform.

Twinning:

None

Physical Properties

Cleavage:

Perfect on {210}, Imperfect on {010} and {100}

Fracture:

Conchoidal

Tenacity:

Brittle

Moh's Hardness:

5.5 - 6.0

Density:

2.85 - 3.57 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Gray, Brownish Gray, Yellowish Brown, Clove-Brown, Brownish Green, Emerald-Green; in thin section, Colorless to pale Green or Yellow

Transparency:

Opaque

Luster:

Vitreous, Pearly on cleavages

Refractive Index:

1.598 - 1.697  Biaxial ( + )

Birefringence:

0.0170 - 0.0230

Dispersion:

Weak to Moderate;  r > v or r < v

Pleochroism:

When Fe-rich, moderate; X = clove-brown, yellowish brown, grayish brown; Y = clove-brown, brown-gray, brownish; Z = clove-brown to dark brown, grayish blue to green, lilac.

Anisotrophism:

Very Strong; Color in reflected light:

Occurances

Geological Setting:

A metamorphic rock. From medium- or high-grade metamorphism, in amphibolites, gneisses, metaquartzites, iron formations, granulites, and schists derived from argillaceous sediments, ultramafic, or mafic igneous rocks; a retrograde reaction product.

Common Associations:

Cordierite, Talc, Chlorite, Sillimanite, Mica, Olivine, Hornblende, Gedrite, Magnesio-Cummingtonite, Garnet, Staurolite, Plagioclase

Common Impurities:

Ti, Al, Mn, Ca, Na

Type Locality:

Nuumite: Nuuk, Vestgronland, Greenland
Anthophyllite: Kjennerud Anthophyllite Prospect, Kjennerud, Kongsberg, Buskerud, Norway

Year Discovered:

Nuumite: 1982
Anthophyllite: 1801
Gerdite: 1836

More Information

Mindat.org  (Nuummite)
Mindat.org  (Anthophyllite)
Mindat.org  (Gedrite)
Mindat.org  (Amphibole Group)
Webmineral.com  (Anthophyllite)
Webmineral.com  (Gedrite)

Nuummite (or Nuumite) is a trade name for a metamorphic rock consisting primarily of two amphiboles; Anthophyllite and Gedrite. It was originally found only in the Godthabsfjord area located in West Greendland near the capital of Nuuk. This material has typically been a black base color with bright iridescent flashes of gold, yellow, copper, red, blue and green. A recent find in the Sahara Desert of Mauritania has produced material with iridescent flashes of deep blue Anthophyllite needles on a black opaque background. This new material discovered in 2009 has been called Sahara Nuummite or Jenakite.

Nuummite is of volcanic origin formed about 3.8 billion years ago making it one of the oldest stones found on earth. Nuummite is also said to have strong metaphysical and spiritual healing properties.
 

  
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