Burangaite, a new phosphate mineral from Rwanda

This paper describes a new phosphate, burangaite, from the Buranga pegmatite in Rwanda. Burangaite is monoclinic with the idealized formula (Na,Ca)2(Fe2+,Mg)2Al10(OH,O)12(PO4)8 ∙ 4H2O, Z = 2. The crystals exhibit narrow, bladed prisms, elongated parallel to the b-axis. Perfect cleavage parallel to 100. Mohs' hardness 5. Streak slightly bluish. Unit-cell data: a0 25.09 Å, b0 5.048 Å, c0 13.45 Å, ß 110.91°, space group C2/c. These parameters and the indexed X-ray powder pattern (Table 1) indicate a marked relationship with dufrenite. The mineral is blue in color with y || b and c/\a = 11°, 2Va = 58°, strong pleochroism, refractive indices α 1.611, ß 1.635, γ 1.643. Common hourglass structure with a blue core and a colorless margin.

Abstract licence: CC BY-NC

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