Sellaite Value, Price, and Jewelry Information

Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons

Sellaite

An overview on Sellaite Jewelry and Gemstones. Covers details and essential information on the physical properties and characteristics of Sellaite gems.

Sellaite Information

Data Value
Name Sellaite
Crystallography Tetragonal: crystals prismatic, acicular, fibrous aggregates.
Refractive Index 1.378-1.390
Colors Colorless, white.
Hardness 5-5.5
Fracture Conchoidal
Birefringence 0.012
Cleavage Poorly observed although literature indicates perfect in 2 directions
Stone Sizes The Brazilian sellaite is the world‘s only extant cuttable material, and the largest crystals found thus far are only 5 cm long with small transparent areas. Thus, gems of only a few carats have or could be produced. This is an exceedingly rare gemstone, both in occurrence and number of cut stones.
Luminescence None reported.
Luminescence Present No
Absorption Spectrum None.
Formula MgF2.
Pleochroism None.
Optics = 1.378; e = 1.390. Uniaxial (+).
Optic Sign Uniaxial +
Luster Vitreous.
Specific Gravity 3.15
Transparency Transparent.

Optics: o=1.378; e= 1.390.

Uniaxial (+).

Occurrence: Sellaite occurs in a wide variety of geological environments.

Vesuvius, Italy: in volcanic fumaroles.

Harz Mountains, Germany: in evaporite beds.

Italy; France: in veins.

Nertschin, Russia: in pegmatites.

Oslo Region, Norway: cavities in a soda-granite.

Brumado Mine, Bahia, Brazil: gemmy crystals in a metamorphic magnesite deposit.

Name: After the Italian mining engineer and mineralogist, Quintino Sella.

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