Francolite

Francolite is a carbonate rich variety of the mineral Fluorapatite[1] and is present in most sedimentary phosphorites. It has a variable chemical composition which can be represented by (Ca, Mg, Sr, Na)10(PO4, SO4, CO3)6F2−3.[2] The mineral was named after its occurrence at Wheal Franco, Whitchurch, Tavistock District, Devon, England.[1]

References

  1. ^ a b http://www.mindat.org/min-4910.html Mindat.org
  2. ^ 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 [1]