Ferberite
with Muscovite Mica and Quartz.
CHEMISTRY Fe WO4
Ferberite forms an isomorphous series between Mn and Fe and includes the minerals Hubnerite and Wolframite.
CRYSTALLOGRAPHY Monoclinic
CRYSTAL GROWTH AND HABITS Commonly prismatic crystals elongated along [010] and flattened. Crystals are often striated. Ferberite is found in groups of bladed crystals or it can be massive.
COLOR AND OTHER OPTICAL PROPERTIES Color and usually opaque.
HARDNESS 4 to 4.5
SPECIFIC GRAVITY 7.51
LUSTER Sub metallic
STREAK Brownish to black
BREAKABILITY Perfect cleavage along [010], with partings along[100] and [102]. Ferberite is brittle
OCCURRENCE Ferberite is found in association with quartz veins or pegmatites near granitic intrusions.
ASSOCIATED MINERALS Quartz, Muscovite, Hematite, Magnetite, Scheelite, Pyrite
Other Properties Ferberite may be slightly magnetic.