Defernite from Güneyce-Ikizdere, Rize Province, Turkey. — Photo: David Hospital · CC BY 4.0
Defernite
Defernite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₆(CO₃)₁.₅₈(Si₂O₇)₀.₂₁(OH)₇[Cl₀.₅₀(OH)₀.₀₈(H₂O)₀.₄₂].
It crystallizes in the orthorhombic crystal system (space group Pnam).
Key properties: specific gravity 2.34–2.5; Pink streak; Vitreous luster; optically biaxial.
IMA symbol Def, IMA status: approved, named in 1978.
Found in skarn at a granite-limestone contact (GÄ _ uneyce-Ikizdere, Turkey); throughout a body of unbanded, granular massive hausmannite (Kombat mine, Namibia).
It is found associated with Vesuvianite, wollastonite, andradite, diopside, calcite, rustumite, spurrite, hillebrandite (GÄ _ uneyce-Ikizdere, Turkey); hausmannite, hillebrandite.
The name refers to Jacques Deferne, Curator of Mineralogy, Museum of Natural History, Geneva, Switzerland.