Francolite

{{Short description|Phosphate mineral}}

{{Infobox mineral

| name = Francolite

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| image = Frankolit1 ,=apatyt,Rosja p Kolski.jpg

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| caption = Francolite found in Russia

| category = Phosphate minerals

| formula = {{chem2|(Ca,Mg,Sr,Na)10(PO4,SO4,CO3)6F_{2–3} }}

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Francolite is a carbonate rich variety of the mineral fluorapatitehttp://www.mindat.org/min-4910.html Mindat.org and is present in most sedimentary phosphorites. It has a variable chemical composition which can be represented by {{chem2|(Ca,Mg,Sr,Na)10(PO4,SO4,CO3)6F_{2–3} }}.R. A. Benmore, M. L. Coleman, and J. M. McArthur, Origin of is sedimentary francolite from its sulphur and carbon isotope composition. Nature 302: 516, 1983 [http://www.nature.com/nature/journal/v302/n5908/abs/302516a0.html] The mineral was named after its occurrence at Wheal Franco, Whitchurch, Tavistock District, Devon, England.