Sellaite
A variety of Minerals
What is Sellaite?
Sellaite is a magnesium fluoride mineral with the formula MgF2. It crystallizes in the tetragonal crystal system, typically as clear to white vitreous prisms. It may be fibrous and occur as radiating aggregates. It has a Mohs hardness of 5 to 6 and a specific gravity of 2.97 to 3.15. Refractive index values are nω = 1.378 and nε = 1.390.
Optical Properties
- Refractive Index
- 1.378-1.390
- Birefringence
- 0.010-0.012
- Optical Character
- Uniaxial negative
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Sellaite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Sellaite Localities Map
See where Sellaite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Formation of Sellaite
Sellaite was first described in 1868 and named for Italian mining engineer and mineralogist Quintino Sella (1827–1884). Its type locality is the glacier de Gébroulaz [fr] in France, where it occurred inside bitumen-bearing dolomite-anhydrite clasts within a moraine deposit. It has been reported in an evaporite deposit at Bleicherode; within volcanic ejecta and fumaroles at Vesuvius; in a metamorphic magnesite deposit at Serra das Éguas [pt]; and in sodic alkali granite near Gjerdingen [no].
Quick Facts
Physical Properties
- Color
- Colourless, white, colourless in transmitted light
- Hardness (Mohs)
- 5 - 5.5
- Density
- 3.08 g/cm³
- Streak
- White
Chemical Properties
- Chemical Formula
- MgF2
- Elements
- F, Mg
Also Known As
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Sellaite FAQs
How do I identify Sellaite?
Sellaite can be identified by its hardness of 5 - 5.5 on the Mohs scale, Colourless color. Look for these key characteristics when examining specimens.
What color is Sellaite?
Sellaite typically appears in Colourless, white, colourless in transmitted light. Color can vary depending on impurities and formation conditions.
How hard is Sellaite?
Sellaite has a hardness of 5 - 5.5 on the Mohs scale. This gives it moderate hardness.
What is the formation of sellaite of Sellaite?
Sellaite was first described in 1868 and named for Italian mining engineer and mineralogist Quintino Sella (1827–1884). Its type locality is the glacier de Gébroulaz [fr] in France, where it occurred inside bitumen-bearing dolomite-anhydrite clasts within a moraine deposit. It has been reported in an evaporite deposit at Bleicherode; within volcanic ejecta and fumaroles at Vesuvius; in a metamorphic magnesite deposit at Serra das Éguas [pt]; and in sodic alkali granite near Gjerdingen [no].
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