Sellaite information

Sellaite
Sellaite
	Sellaite crystal from Serra das Éguas, Brazil (size: 4.2 x 2.4 x 2 cm)
General
Category	Halide mineral
Formula; (repeating unit)	MgF2
IMA symbol	Sel
Strunz classification	3.AB.15
Crystal system	Tetragonal
Crystal class	Ditetragonal dipyramidal (4/mmm) ; H-M symbol: (4/m 2/m 2/m)
Space group	P42/mnm
Unit cell	a = 4.6213(2) ; c = 3.0519(1) [Å]; Z = 2
Identification
Color	Colorless to white
Crystal habit	Prismatic crystals; fibrous, radial, spherulitic
Twinning	On {011}
Cleavage	Perfect on {010} and {110}
Fracture	Conchoidal
Tenacity	Brittle
Mohs scale hardness	5–5.5
Luster	Vitreous
Diaphaneity	Transparent
Specific gravity	3.15
Optical properties	Uniaxial (+)
Refractive index	nω = 1.378; nε = 1.390
Birefringence	δ = 0.012
References

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 n_ω = 1.378 and n_ε = 1.390.

^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
^ Mineral Data Publishing: Handbook of Mineralogy
^ Mindat with location data
^ Webmineral data

[1] Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.

[HBM-2] Mineral Data Publishing: Handbook of Mineralogy

[Mindat-3] Mindat with location data

[Webmin-4] Webmineral data

Sellaite information

and 10 Related for: Sellaite information

Sellaite

Magnesium fluoride

List of gemstones by species

Quintino Sella

List of minerals

Ol Doinyo Lengai

List of mineral symbols

Halide mineral

Geology of Tasmania

List of minerals named after people