Mineral Class: Quartz
Crystal System: Trigonal
Hardness: 4 - 5
Diaphaneity: Transparent to Translucent
Colors: Black, Purple, White
Indigo Gabbro is a combination of multiple minerals containing Feldspar, Chlorite, Serpentine, Muscovite, Pyroxene, Hercynite, and Magnetite in a charcoal colored matrix; it may also contain small amounts of Olivine, Chrome Garnet, Actinolite, and Biotite. Indigo Gabbro occurs in the indigo and violet ranges of color, and darker, often occurring as black. The stone’s name is two fold, it’s color variation is an easy read for naming. Indigo Gabbro was named by the German geologist Christian Leopold von Buch after a town in the Italian Tuscany region. However, Indigo Gabbro refers to a large group of dark, coarse-grained, protruding igneous rocks similar in chemical structure to basalt. The rocks are formed when molten magma is trapped beneath the Earth's surface and cools into a crystalline mass. Indigo Gabbro occurs in most of earth’s oceanic crusts, especially in mid-ocean ridges. Indigo Gabbro can sometimes contain valuable amounts of chromium, nickel, cobalt, gold, silver, platinum, and copper sulfides. Ocellar varieties of Indigo Indigo Gabbro can be used as paving stones and it is also known by the trade name 'black granite', used in kitchens and their countertops.