Francolite
Image: No machine-readable author provided. Kluka assumed (based on copyright claims). (CC BY-SA 3.0)
Mineral NameFrancolite
Chemical FormulaCa₅(PO₄,CO₃)₃F
Mohs Hardness5
Crystal Systemhexagonal
Streak Colorwhite
Cleavageimperfect on {0001} and {1010}
Fractureconchoidal/uneven
Specific Gravity3.1
Colorspale greenish-blue, white, gray, brown
Transparencytranslucent
Type LocalityKhibiny Massif, Kola Peninsula, Russia
Mineral GroupPhosphates
Usesfertilizers, collector
Associated Mineralsnepheline, aegirine, feldspar, titanite
Raritycommon
Description
A specimen featuring a pale greenish-blue, botryoidal coating of francolite covering a greyish, granular host rock. The surface is composed of numerous small, rounded, grape-like aggregates.
Geological Context
Francolite is a carbonate-rich variety of fluorapatite, commonly found in sedimentary phosphorite deposits, but also occurs in igneous rocks, particularly alkaline complexes and carbonatites, where it can form significant ore bodies.
