Weberite

weberite

prosopite

cryolite

hydrokenoralstonite

Formula: Na₂MgAlF₇
Halide
Crystal System: Orthorhombic
Specific gravity: 2.96 measured, 2.966 calculated
Hardness: 3½
Streak: White
Colour: Greyish white; colourless in transmitted light.
Solubility: Slightly soluble in water. Readily soluble in an AlCl₃ solution (Mindat).
Environments

Pegmatites

Weberite occurs with cryolite and other fluorides (Webmin).

At the type locality, the Ivigtut Cryolite deposit, Sermersooq, Greenland, Denmark, weberite occurs in a cryolite deposit and overlying pegmatite associated with cryolite, chiolite, jarlite, stenonite, thomsenolite, prosopite, pachnolite, hydrokenoralstonite, fluorite, topaz, potassian mica, pyrite, quartz, feldspar, siderite and galena (HOM, Mindat, AM24.278).
Weberite from Ivigtut - Image

At the Eureka Tunnel (1-15 pegmatite), St Peters Dome, Cheyenne Mining District, El Paso County, Colorado, USA, brick red weberite with pale grey quartz and grayish pink K-feldspar has been found (Mindat photo).
Weberite from the Eureka Tunnel - Image

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