ilvaite

from The Century Dictionary.

• noun A silicate of iron and calcium occurring in black prismatic crystals. It is found in the island of Elba and elsewhere. Also called lievrite and yenite.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Min.) A silicate of iron and lime occurring in black prismatic crystals and columnar masses.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun mineralogy A black, crystalline sorosilicate of iron and calcium