Cacoxenite Inclusion in Amethyst.
CHEMISTRY - Fe24AlO6(PO4)17(OH)12.n2HO (n is about 75)
CRYSTALLOGRAPHY - Hexagonal
CRYSTAL GROWTH AND HABITS - Most commonly Cacoxenite forms acicular, compact spherical masses. It may also occur in bundles, tufted aggregates or as a cement between mineral grains and as a vein filling material.
COLOR AND OPTICAL PROPERTIES - Yellowish to brown to reddish brown and rarely greenish; transparent to translucent
HARDNESS - 3 - 4
SPECIFIC GRAVITY - 2.2 - 2.6
LUSTER - Silky
STREAK - Light yellow
BREAKABILITY - The only information I have to date is that it has poor cleavage. I am still looking for more information.
OCCURRENCE - Cacoxenite is a common mineral in the oxidized zone of iron deposits.
ASSOCIATED MINERALS - Limonite, Dufrenite, Rockbridgeite, Beraunite, Strengite, Wavellite, Magnetite
MINERAL NAME - From the Greek for "bad guest" due to the fact that the phosphorous content of Cacoxenite lessons the quality of the smelted iron.