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
Colors Colorless, white.
Crystallography Tetragonal: crystals prismatic, acicular, fibrous aggregates.
Refractive Index 1.378-1.390
Luster Vitreous.
Hardness 5-5.5
Fracture Conchoidal
Specific Gravity 3.15
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
Transparency Transparent.
Absorption Spectrum None.
Formula

MgF2.

Pleochroism

None.

Optics

= 1.378; e = 1.390. Uniaxial (+).

Optic Sign Uniaxial +

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.