Francolite

Francolite is a carbonate rich variety of the mineral fluorapatite and is present in most sedimentary phosphorites. It has a variable chemical composition which represented by (Ca,Mg,Sr,Na)10(PO4,SO4,CO3)6F2-3. The mineral named after its occurrence at Wheal Franco, Whitchurch, Tavistock District, Devon, England.

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