triploidite

from The Century Dictionary.

• noun A phosphate of iron and manganese occurring in monoclinic prismatic crystals, also in columnar to fibrous masses of a reddishbrown color. It closely resembles triplite, but differs from it in having the fluorin replaced by hydroxyl.

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

• noun (Min.) A manganese phosphate near triplite, but containing hydroxyl instead of fluorine.

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

• noun mineralogy An uncommon monoclinic manganese iron phosphate mineral.