Brandtite

6 in the gallery

Brandtite is a rare arsenate mineral with calcium, manganese, and arsenate groups in its structure. It typically forms as colorless to pale green crystals that can occur as elongated, prismatic aggregates with a vitreous to subadamantine luster. The mineral’s composition—Ca2Mn2+ (AsO4)2 · 2H2O—reflects its hydration and arsenate-bearing framework, and it often presents in microcrystalline to crystalline forms that are sought after by specialists. Distinguished specimens have come from localities in the United States and northern Europe, where secondary and metamorphic environments can promote its growth. The combination of delicate crystal habit, hydration, and arsenate chemistry makes Brandtite a standout among manganese- and calcium-bearing arsenates, attracting collectors who focus on rare, descriptor-rich constituents.