Wiktionary
messelite
n. (context mineralogy English) A triclinic-pinacoidal mineral containing calcium, hydrogen, iron, manganese, oxygen, and phosphorus.
Wikipedia
Messelite
Messelite is a mineral with formula Ca(Fe,Mn)(PO)ยท2HO. It was discovered in Germany and described in 1890. The mineral was subsequently discredited in 1940, reinstated and named neomesselite in 1955, and the name restored to messelite in 1959.