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Formula: Ca3Zr2(SiFe3+2)O12
Nesosilicate (insular SiO4 groups), schorlomite group,
garnet supergroup,
zirconium-bearing mineral
Crystal System: Isometric
Specific gravity: 4.105 calculated
Hardness: 7
Colour: Light to dark brown
Environments
Carbonatites
Metamorphic environments
Localities
At Zlatno, Vysoká, Banská Štiavnica District, Banská Bystrica Region, Slovakia, kerimasite has been identified
in association with
andradite, grossular and their
hydrated analogues, monticellite,
perovskite, clintonite,
anhydrite,
hydroxylellestadite
fluorellestadite, spinel,
magnetite, brucite,
valleriite and other minerals from a Ca-Mg
skarn in the exocontact (on the
skarn side of the contact) of a
granodiorite
porphyry intrusion in a Cu-Au
skarn porphyry deposit.
Kerimasite forms euhedral-to-anhedral crystals, 2 to 100 microns across. The crystals commonly show regular,
oscillatory concentric zoning.
Kerimasite and associated skarn minerals originated during
contact thermal metamorphism at temperature ~700oC
and pressure ~70 MPa (0.7 kbar)
(MM 79.3.715-733).
At the type locality, the Kerimasi volcano, Monduli District, Arusha Region, Tanzania, Kerimasite occurs as
subhedral crystals up to 100 microns in size in calcite
carbonatites, and as euhedral to subhedral crystals up to
180 microns in size in carbonatite eluvium.
Kerimasite is light to dark brown in colour and transparent with a vitreous lustre. No cleavage or parting was
observed and the mineral is brittle
(MM 74.5.803-820).
Associated minerals include calcite, and rarely
fluorapatite and
magnesioferrite
(HOM).
At Magnet Cove, Hot Spring County, Arkansas, USA, kerimasite has been found with
perovskite
(Mindat photo).
Kerimasite from Magnet Cove -
Image
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