Sellaite Value, Price, and Jewelry Information

view gemstone encyclopedia

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

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.
Crystallographic Forms
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.

Ready to learn how to identify gems on your own?

Join our mailing list below to download a FREE gem ID checklist tutorial. See what’s inside…

• Discover the 17 practical steps to gemstone identification (even if you’re just getting started with gemology)

• Learn how you can use specific tools to gather data, make observations & arrive at an accurate ID

• Explore a range of gemological tests… not only will you get familiar with the process but also time-saving shortcuts!