CHEMISTRY - MgAl2O4
CRYSTALLOGRAPHY - Cubic
CRYSTAL GROWTH AND HABITS - Spinel is commonly found as octahedrons, sometimes modified by dodecahedral or cubic faces. It can also be coarse granular or massive.
COLOR AND OPTICAL PROPERTIES - Colorless to brown, black, red, orange yellow, green, blue and violet. Transparent to translucent.
HARDNESS - 7.5 - 8
SPECIFIC GRAVITY - 3.6 - 4.1
LUSTER - Vitreous to dull
STREAK - White
BREAKABILITY - The fracture of Spinel is conchoidal, uneven to splintery. It is brittle.
OCCURRENCE - Spinel is found as an accessory mineral in high temperature igneous rocks like basalts and kimberlites. It is also found in regionally metamorphosed aluminum rich schists and limestones.
ASSOCIATED MINERALS - Fosterite, Scapolite, Phlogophite, Corundum, Sillimanite, Andalusite.
MINERAL NAME - The name may be derived from the Latin spinella for "little thorn", in reference to its octahedral crystals.