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Formula: Ca6(CO3)1.58(Si2O7)0.21(OH)7[Cl0.50(OH)0.08 (H2)0.42]
Hydrated carbonate containing hydroxyl
Specific gravity: 2.34 to 2.5
Hardness: 3
Streak: Colourless, also pink
Colour: Colourless (original occurrance), also deep red, rose-brown
Solubility: Dissolves in l:l hydrochloric acid with effervescence
Common impurities: Fe,Mn,Mg
Environments
Metamorphic environments
Hydrothermal environments
Defernite is a rare carbonate reported from only two sites to date (May 2020)
Localities
At the type locality, Güneyce-Ikizdere, Rize Province, Turkey, defernite is a
secondary alteration product of high-temperature calc-silicates occurring in
skarn at the contact of granite with
limestone. Associated minerals include vesuvianite,
wollastonite, andradite,
diopside, calcite,
rustumite, spurrite and
hillebrandite
(AM 65.1066, Dana).
At the Kombat Mine, Grootfontein, Otjozondjupa Region, Namibia, defernite is distributed through a body of massive, granular
hausmannite. Subhedral grains of brucite fill spaces
between, or partially include, hausmannite and
hillebrandite. Small amounts of crednerite are
found within the hausmannite. Native copper is a ubiquitous
associate, occasionally forming thin films along multiple cleavage planes in the defernite, and appears to have replaced it in part.
Granular baryte, calcite and
vesuvianite are also common associates. Crednerite,
jacobsite and hematite are less common. Rarely,
late-stage veins of calcite were observed intergrown with defernite and arborescent growths
of native copper. The defernite-bearing hausmannite
ore occurs immediately above glaucochroite- and
harkerite-bearing zones
(AM 73.888-893).
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