Johntomaite
Johntomaite is an IMA-recognized mineral species in the phosphate class, with the chemical formula BaFe²⁺₂Fe³⁺₂(PO₄)₃(OH)₃.
It crystallizes in the monoclinic crystal system (space group P2_1/m). It is a member of the Bjarebyite structural group.
Key properties: Mohs hardness 4.5; specific gravity 4.05; Dark grayish green streak; Vitreous, greasy to subadamantine luster; optically biaxial.
IMA symbol Jtm, IMA status: approved, named in 1999.
Found in a brecciated, low-temperature, hydrothermal vein.
It is found associated with Quartz, libethenite, pseudomalachite, mitridatite, goethite, cuprite, copper.
The mineral was named to honor Mr. John Toma (b. 1954), amateur mineralogist who first found the mineral.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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