Heterosite (size: 3.5" x 2.5" x 1.5") Locality: Newry, Oxford County, Maine, USA original description: Seriously purple old collection specimen of heterosite (labeled pupurite) from Newry, Maine. — Photo: John Krygier · Public domain
Heterosite
Heterosite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Fe³⁺(PO₄).
It crystallizes in the orthorhombic crystal system (space group Pbnm). It is a member of the Olivine structural group.
Key properties: Mohs hardness 4–4.5; specific gravity 3.4; Pale purple streak; Satiny on fresh surfaces, dull to earthy luster; optically biaxial.
IMA symbol Het, grandfathered status — known before the IMA’s founding, named in 1826.
Found as a secondary mineral in the oxidized zone of complex granite pegmatites, replacing primary phosphate minerals, principally triphylite.
It is found associated with Triphylite, ferrisicklerite, many secondary Fe–Mn phosphates.
Its name comes from the Greek for another, probably because it was the second manganese-bearing species described from the type locality.