Sellaite

minerals

anhydrite

gypsum

magnesite

Formula: MgF2
Normal halide
Specific gravity: 3.15
Hardness: 5
Streak: White
Colour: Colourless or white, colourless in transmitted light
Solubility: Slightly soluble in water. Decomposed by concentrated sulphuric acid
Environments

Igneous environments
Evaporite deposits
Fumeroles

Sellaite occurs in evaporites, volcanic ejecta and fumeroles, marble, magnesite and alkalic granite. Anhydrite, gypsum and sulphur are common associates (Mindat).

Localities

At the Pedra Preta pit, Serra das Éguas, Brumado, Bahia, Brazil, sellaite occurs in vugs associated with magnesite and quartz (Dana).

At the type locality, the Gébroulaz glacier, Val Thorens, Saint-Martin-de-Belleville, Les Belleville, Albertville, Savoie, Auvergne-Rhône-Alpes, France, sellaite occurs in bituminous dolomite-anhydrite rock in a glacial moraine (Dana). Associated minerals include fluorite, anhydrite, dolomite, celestine, quartz and sulphur (Mindat).

At Carrara, Massa-Carrara Province, Tuscany, Italy, sellaite occurs in cavities in marble (Dana).

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