Wiktionary
zemannite
n. (context mineralogy English) A hexagonal-dipyramidal mineral containing hydrogen, iron, magnesium, oxygen, tellurium, and zinc.
Wikipedia
Zemannite
Zemannite is a very rare oxide mineral with the chemical formula MgZnFe[TeO]ยท4.5HO. It crystallizes in the hexagonal crystal system and forms small prismatic brown crystals. Because of the rarity and small crystal size, zemannite has no applications and serves as a collector's item.