Stibiotantalite
Current inventory:  0 gems
 

  
Stibiotantalite is named from its Antimony (Sb) content (the Greek word for Antimony is stibio) and its relation to Tantalite.

Discovered in 1893; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Sb(Ta,Nb)O₄

Antimony Tantalum Oxide

Molecular Weight:

366.70 gm

Composition:

Tantalum

49.35 %

Ta

60.25 %

Ta₂O₅

Antimony

33.20 %

Sb

41.93 %

SbO₂

Oxygen

17.45 %

O

100.00 %

102.18 %

= TOTAL OXIDE

Classification

Mineral Classification:

Oxides

Strunz 8th Ed. ID:

4/D.25-30

Nickel-Strunz 10th Ed. ID:

4.DE.30

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
E : With medium-sized cations; with various polyhedra

Related to:

Cervantite Group. Stibiocolumbite - Stibiotantalite Series.

Members of Group:

Cervantite Group: Bismutocolumbite, Bismutotantalite, Cervantite, Clinocervantite, Stibiocolumbite, Stibiotantalite

Varieties:

Bismuthian Stibiotantalite

Synonyms:

None

Crystal Data

Crystallography:

Orthorhombic - Pyramidal

Crystal Habit:

Crystals prismatic || [010], flattened || to [001], may be equant, to 12 cm; {001} and {101} striated || [010].

Twinning:

About [010] with composition plane {001}; polysynthetic.

Physical Properties

Cleavage:

Distinct on {001}, Indistinct on {100}

Fracture:

Sub-Conchoidal

Tenacity:

Brittle

Moh's Hardness:

5.5

Density:

5.98 - 7.53 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Yellow, greenish yellow, yellowish brown, reddish brown, brown

Transparency:

Transparent to Translucent

Luster:

Adamantine to Resinous

Refractive Index:

2.374 - 2.457  Biaxial ( + )

Birefringence:

0.0826

Dispersion:

0.146; Relatively Strong; r < v

Pleochroism:

Colorless

Occurances

Geological Setting:

An uncommon accessory mineral in complex granite pegmatites.

Common Associations:

Tantalite (Greenbushes, Western Australia); Antimony, Allemontite, Microlite, Stibiomicrolite, Lithiophilite, alkalic Beryl, Cassiterite, Columbite–Tantalite (Varuträsk, Sweden).

Common Impurities:

Nb

Type Locality:

Greenbushes Sn placers, Greenbushes Tinfield, Western Australia, Australia

Year Discovered:

1893

View mineral photos:

Stibiotantalite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Stibiotantalite is extremely rare as a faceted gem. Stibiotantalite crystals are fairly rare and usually almost opague or very heavily included, so transparent gems are extremely rare. Stibiotantalite is strongly birefringent which may give gems with any clarity a sleepy look due to doubling of the back facets when seen through the table. Clean, facetable crystals are extremely rare.

These locations may be th only sources of facetable crystals: Rio Grande do Norte, Brazil; Alto Ligonha District, Zambezia Province, Mozambique; and in the USA at San Diego County, California.

Distribution: From the Greenbushes tin placers, Wodgina district, Western Australia. Large crystals at the Muiâne and other mines, Alto Ligonha, Mozambique. From the Benson mine, Mtoko, Zimbabwe. In the USA, from Topsham, Sagadahoc County, Maine; in California, in San Diego County, fine crystals from the Himalaya mine, Mesa Grande district; at the Katerina, Stewart, and Vandenburg mines, Pala district; and in the Little Three mine, Ramona district; in the Brown Derby pegmatite, Gunnison County, Colorado. In the Varuträsk pegmatite, 15 km northwest of Skellefteå, Västerbotten, Sweden. From the Voronya massif, Kola Peninsula, Russia. Found near Stak Nala, Gilgit district, Pakistan.
 

  
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