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Formula: K(Fe3+Si3O8)
Tectosilicate (framework silicate), alkali feldspar subgroup,
feldspar group
Crystal System: Monoclinic
Specific gravity: 2.722 calculated
Streak: White
Colour: Colourless to white
Environments
Ferrisanidine is a relatively new mineral, approved in 2019.
Localities
At the type locality, the Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure eruption,
Tolbachik Volcanic field, Milkovsky District, Kamchatka Krai, Russia, the temperature measured in the area during
the collecting of samples with ferrisanidine was ~400°C. It is noteworthy that the sublimates of the
Arsenatnaya fumarole contain rich silicate mineralisation including
feldspars.
Sanidine–filatovite,
anorthoclase and
plagioclase (from andesine to
anorthite) are quite common here. Ferrisanidine is the rarest
feldspar in this fumarole. It is associated with
aegirine, cassiterite,
hematite, sylvite,
halite, johillerite,
badalovite, arsmirandite,
axelite, aphthitalite,
litidionite, tridymite,
polyarsite and evseevite
(Minerals 9.12.770).
Ferrisanidine from the Arsenatnaya
fumarole - Image
At the Leucite Hills Mining District, Sweetwater County, Wyoming, USA, ferrisanidine has been found in
lamproite
(HOM).
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