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Diaspore
Current inventory:  1 gem
 

Chemistry:  AlO(OH)

Discovered in 1801;   IMA status: Valid (pre-IMA; Grandfathered).
The name Diaspore is from the Greek word diaspeirein, meaning to scatter, because the mineral falls apart easily under the flame of a blowpipe.

Classification

Mineral Classification:

Hydroxides

Strunz 8th Ed. ID:

4/F.06-10

4 : Oxides & Hydroxides
F : Hydroxides and oxidic hydrates, water-bearing oxides with layered structure
06 : Diaspore - Goethite - Faitknechtite series

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

As crystals, platy and elongated to acicular, to 40 cm; stalactitic, foliated, scaly; disseminated, massive. Twinning: to form heart-shaped twins or pseudohexagonal aggregates.

Physical Properties

Cleavage:

[010] Perfect, [110] distinct, [100] in traces

Fracture:

Conchoidal

Tenacity:

Very Brittle

Moh's Hardness:

6.5 - 7.0

Density:

3.20 - 3.50 (g/cm³)

Radioactivity:

Not Radioactive

Optical Properties

Color:

White, pale gray, colorless, greenish gray, brown, pale yellow, pink, lilac; color may vary with viewing direction in the same specimen, may show a color change from brownish green in daylight to raspberry pink in artificial light.

Transparency:

Transparent to Translucent

Luster:

Adamantine, Vitreous, Pearly on cleavage faces.

Refractive Index:

1.700 - 1.752  Biaxial ( + )

Birefringence:

0.047 - 0.050

Dispersion:

Weak

Pleochroism:

Strong; may be reddish brown to reddish violet; grayish green to green.

Occurances

Geological Setting:

Typically a final product of diagenesis in bauxite deposits formed by the tropical weathering of alumino-silicate rocks; from hydrothermal alteration of aluminous minerals; a hydrothermal mineral in some alkalic pegmatites.

Type Locality:

Mramorsk (Mramorskoye) Zavod, Kosoi Brod Village, Ekaterinburg (Yekaterinburg; Sverdlovsk), Sverdlovskaya Oblast', Urals Region, Russia

Year Discovered:

1801

View mineral photos:

Diaspore Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Diaspore is a very rare gem with gem quality crystals coming mainly from bauxite deposits at Mamaris, Yatagan, Mugla Province, Turkey. It is hard enough for use in jewelry, but too brittle. Some gems have very strong pleochroism with colors changing from pale golden-green to mauve-brown. Very rarely, gems may display colors of violet-blue and dark red.
 

  
Diaspore gems for sale: