A good size crystal of columbite-(Mn) that shows parallel growths on the faces, with striations, intense luster and black color. The accompanying handwritten label indicates that it belongs from the Etiro pegmatites, in Namíbia, a locality of which few specimens have been seen in the market. The piece belongss from H.G. Hoppert. Sample has been analyzed and the results, as can be seen in the attached documents, indicate it contains more Mn than Fe, a columbite, but with values of Nb-Ta in the border area with tantalite domain. All results will be sent to the buyer.

Sold

These specimens show yellowish nodules included in a feldspar matrix. First SEM-EDS analysis have yielded a phosphate of Th and Ca, with minor Pb. XRD has shown patterns of "bravantite", the old name for cheralite and brockite. The chemical base formula for these species are: grayite (Th,Pb,Ca)(PO4)·H2O; cheralite CaTh(PO4)2; brockite (Ca,Th,Ce)(PO4)·H2O. REE has not been found in EDS.
We could say that this yellow nodules belongs from altered monazite, formed by mixed species cheralite-grayite, with minor brockite. Accompanied in matrix by meta-autunite. We will send the full report.

Sold