Drusy Mottramite crystals completely coating wulfenite crystals.
CHEMISTRY PbCu(VO4)(OH)
CRYSTALLOGRAPHY Orthorhombic
CRYSTAL GROWTH AND HABITS Single Mottramite crystals are rare and are prismatic dipyramidal. Typically Mottramite forms drusy coatings, crusts or is botryoidal. It is also granular to massive.
COLOR AND OTHER OPTICAL PROPERTIES Mottramite is brownish black to black and also greenish. It is translucent to opaque.
HARDNESS 3 - 3.5
SPECIFIC GRAVITY 5.9 - 6.0
LUSTER Crystals have a greasy luster.
STREAK Black to greenish black
BREAKABILITY Subconchoidal to uneven, brittle
OCCURRENCE Mottramite is formed as a secondary mineral in the oxidized zone of vanadium deposits.
ASSOCIATED MINERALS Descloizite, Mimetite, Wulfenite, Cerussite, Azurite