One of the tantalite minerals. Multiple oxide, columbite group, orthorhombic paramorph of tetragonal tapiolite-(Fe), forms a series with tantalite-(Mn) and with columbite-(Fe), tantalum-bearing mineral
Specific gravity: 8.2
Hardness: 6 - 6½
Colour: Brownish black, black
Solubility: Insoluble in hydrochloric and nitric acid; slightly soluble in sulphuric acid
Tantalite-(Fe) is an accessory mineral in granite
At the Lipovsk pegmatite field, Rezhevsky District, Sverdlovsk Oblast, Russia, intergrowths of tantalite-(Mg), tantalite-(Fe), columbite-(Fe) and uranium-bearing microlite form rims on tantalite-(Mn) crystals in albite variety andesine-calcite nests in a deeply desilicated granite pegmatite which crosscuts serpentinite near its contact with marble. Other associated minerals include dravite-uvite, chrysoberyl, phlogopite, magnesio-hornblende to edenite, cordierite, phenakite and clinochlore (Minrec 35.4.356-357).
The type locality is Upper Bear Gulch, Tinton Pegmatite Mining District, Lawrence county, South Dakota, USA.
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