Orthobrannerite
Orthobrannerite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula U⁴⁺U⁶⁺Ti₄O₁₂(OH)₂.
It crystallizes in the orthorhombic crystal system (space group P222_1). It is a member of the Brannerite structural group.
Key properties: specific gravity 5.46; Dark brown to black streak; Adamantine luster.
IMA symbol Obnr, IMA status: approved, named in 1978.
Found in weathered biotite pyroxene syenite (Yunan, China); in an alkalic lamprophyre (Szechwan, China).
As an ORTHOrhombic dimorph of brannerite.
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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