Tags: Chemical Substance, Mineral.
Simpsonite has a general formula of Al4(TaNb)3O13(OH). It occurs as euhedral to subhedral tabular to short and prismatic crystals commonly in subparallel groups. Under the petrographic microscope it has a very high relief. It was named after Edward Sydney Simpson (1875–1939) government mineralogist and analyst of Western Australia. It is an accessory mineral in some tantalum-rich granite pegmatites.
