from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An orthorhombic-dipyramidal mineral containing boron, iron, magnesium, and oxygen.
from the GNU version of the Collaborative International Dictionary of English
- n. A borate of iron and magnesia, occurring in fibrous masses of a blackish green color.
from The Century Dictionary and Cyclopedia
- n. A borate of iron and magnesium, occurring in dark-green to black masses with a fine fibrous structure.