Poldervaartite and Bultfonteinite

Poldervaartite and Bultfonteinite, N'Chwaning, Kuruman, South Africa. In a Perki's box, an excellent specimen of these two minerals. Poldervaartite are the light brown crystals, a calcium hydroxy silicate, and bultfonteinite are the white fibres, a calcium fluoro silicate, excellent for macro photography. Label from a collection assembled by a collaborator of the Natural History Museum in Paris with very precise localities and determinations.