thomsenolite


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thomsenolite

[′täm·sə·nə‚līt]
(mineralogy)
NaCaAlF6·H2O A colorless to white, monoclinic mineral consisting of a hydrated aluminofluoride of sodium and calcium; it is dimorphous with pachnolite.
References in periodicals archive ?
Associated minerals in addition to gibbsite and thomsenolite are doyleite, pyrrhotite, sphalerite, galena, pyrite and a pale yellow unidentified mineral.
Recently doyleite was also found in contact-zone cavities as white, powdery aggregates admixed with gibbsite and associated with thomsenolite and cryolite.
In a very rare and unusual mineral assemblage, gibbsite was found as cavity fillings in the contact zone in close association with cryolite, thomsenolite and doyleite.
At all these localities thomsenolite is associated with cryolite, as it invariably evolves as an alteration product of cryolite (Bailey, 1980).
Thomsenolite forms the walls and wall linings of a dense network of small solution cavities 2-15 mm in diameter.
It is also found associated with thomsenolite, topaz, phenakite, cryolithionite and fluorite (Palache et al.
Peter's Dome, El Paso County, Colorado, where microcrystalline aggregates are found sparingly with pachnolite, cryolite, prosopite, thomsenolite and gearksutite in aluminum fluoride pegmatites.
Thomsenolite and pachnolite are dimorphous forms which generally occur together in cryolite solution cavities.
Pachnolite is biaxial positive with 2V = 76[degrees], and thomsenolite is biaxial negative with 2V = 50[degrees].
Thomsenolite is clear, colorless, and characteristically forms aggregates of blocky crystals in parallel orientation.