Ilvaite

Ilvaite is a sorosilicate mineral with the chemical formula Ca2Fe2+2Fe3+(SiO4)2(O2OH). It is also known as lievrite. Its crystal system is monoclinic and it typically forms prismatic or granular aggregates. Ilvaite is usually dark brown to black in color, though it can also be found in greenish-black hues. It possesses a vitreous to submetallic luster. A notable characteristic of ilvaite is its high specific gravity, which ranges from 3.8 to 4.1.

The mineral was first discovered in 1797 at the Elba iron mine on the island of Elba in Tuscany, Italy, and was named after the island's ancient name, Ilva. Ilvaite is a relatively rare mineral, found in metamorphosed iron deposits, skarns, and certain contact metamorphic rocks. It often occurs in association with other minerals such as garnet, epidote, and magnetite. While not a commercially significant ore mineral, ilvaite is of interest to mineral collectors and geologists for its unusual composition and occurrence. Microscopic inclusions within ilvaite can sometimes create interesting optical effects.