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Formula: NaCaAlF6.H2O
Halide, paramorph of
thomsenolite,
which is epitaxial on pachnolite
Crystal System: Monoclinic
Specific gravity: 2.98
Hardness: 3
Streak: White
Colour: Colourless, white; colourless in transmitted light.
Solubility: Soluble in sulphuric acid, easily fusible (Dana)
Environments
Pachnolite occurs as an alteration product of cryolite and other alkali
aluminium fluorides, most commonly in pegmatites. Associated minerals include
cryolite, thomsenolite,
chiolite, elpasolite,
hydrokenoralstonite,
sellaite and
fluorite (HOM).
At the type locality, the Ivigtut Cryolite deposit, Sermersooq, Greenland, Denmark, pachnolite occurs as an
alteration product
of cryolite (Dana), associated with
thomsenolite (Mindat).
At Saint Peter's dome, El Paso county, Colorado, USA, pachnolite occurs with
thomsenolite, elpasolite and
other fluorides (Dana).
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