Seamanite

Seamanite is a very rare manganese boron phosphate, Mn3(PO4)B(OH)6, first discovered in Michigan under the name "koenigite". The only known occurrences have been Iron and Marquette Counties in Michigan, where it forms brown to pink prismatic crystals. It has been found associated with shigaite.

It is named in honor of late Professor Arthur E. Seaman of Michigan Technological University who discovered it.