CHEMISTRY - CaFe2(FeO)Si2O7(OH)
CRYSTALLOGRAPHY - Orthorhombic and Monoclinic
CRYSTAL GROWTH AND HABITS - Crystals of Ilvaite are commonly prismatic with striations parallel to the "C" axis. It can also be columnar in radiating or stellate groups. It can also be massive.
COLOR AND OPTICAL PROPERTIES - Ilvaite is most commonly black or dark grayish black. It is Opaque to slightly translucent along thin edges.
HARDNESS - 5.5 - 6
SPECIFIC GRAVITY - 3.9 - 4.06
LUSTER - Vitreous to sub metallic
STREAK - Black
BREAKABILITY - Ilvaite has a well developed cleavage along {001} and {010} and an uneven fracture. It is brittle.
OCCURRENCE - Ilvaite is found in contact metamorphic rocks and in iron rich rocks.
ASSOCIATED MINERALS - Magnetite, Hedenbergite, Quartz, Fluorite
MINERAL NAME - From the Latin name "Ilva" for Elba - the island where it was first found.