What is Olmiite?
Olmiite is a pink manganese-rich member of the pyroxenoid family, prized for its colour and association with manganese ore and skarn systems.
Mineralogy and crystal structure
Reference formula: CaMn2+SiO3(OH). Olmiite is closely related to pectolite and serandite, with manganese occupying key sites in an orthorhombic framework. Composition and colour can grade toward related minerals. Olmiite is classified with silicates and has a orthorhombic crystal system. Typical hardness is 4.5–5 on the Mohs scale and specific gravity is approximately 3.1–3.3.
Colour, lustre and habit
Typical colours include pink, salmon, orange, brown. The usual prismatic, fibrous, massive habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Olmiite forms in or is associated with manganese-rich skarns, metamorphosed ore deposits and hydrothermal manganese assemblages. Important documented localities include Japan, Sweden, Italy, South Africa and manganese districts of the United States.
Soft pink manganese in a hard-rock setting
Olmiite pairs a friendly salmon colour with serious structural complexity. Its pyroxenoid chains show how manganese-rich fluids can create unusual minerals in skarn environments.
Collecting and care
Avoid acids and abrasion; preserve the matrix because associations help separate it from similar pink silicates.
