What is Natrophilite?
Natrophilite is a sodium manganese phosphate of lithium-rich granitic pegmatites, valued for warm colour and its ordered olivine-type structure.
Mineralogy and crystal structure
Reference formula: NaMnPO4. Natrophilite is an orthorhombic phosphate with ordered sodium and manganese sites. Oxidation can produce darker alteration and secondary manganese phosphates, so fresh faces and matrix are informative. Natrophilite is classified with phosphates and has a orthorhombic crystal system. Typical hardness is 4–5 on the Mohs scale and specific gravity is approximately 3.4–3.6.
Colour, lustre and habit
Typical colours include yellow, orange, brown, pink. The usual prismatic, granular, massive habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Natrophilite forms in or is associated with phosphate-rich granitic pegmatites and late-stage lithium-bearing pockets. Important documented localities include the United States, Brazil, Sweden, Canada, Madagascar and Portugal.
Warm phosphate colour in a lithium pegmatite
Natrophilite adds a distinctive orange-yellow note to a pegmatite suite and shows how sodium and manganese order themselves in a late-stage phosphate structure.
Collecting and care
Protect from abrasion and weathering; keep the pegmatite association intact.
