Summary: Manganhumite, orthorhombic, a 10·54(1), b 21·45(2), c 4·822(9) Å, space group Pnma, Z = 4, (Mn_0·68Mg_0·30Fe_0·01Ca_0·01)₇(OH)₂(SiO₄)₃, is the manganese analogue of humite whose type locality is the Brattfors mine, Nordmark, Province of Värmland, Sweden. It is a skarn assemblage mineral and occurs with katoptrite, manganostibite, magnussonite, galaxite, etc., which replace manganosite grains in magnetite-manganosite ore.

The mineral is biaxial (+), α = 1·707(3), β = 1·712(3), 7 = 1·732(3), 2V₇(obs.) = 37(4)° r > v perceptible, cleavage {010} perfect, hardness = 4, specific gravity = 3·83(5). The five strongest powder lines are 1·777(10), 2·500(7), 3·371(6), 2·628(6), and 1·525(6).