Francolite
Encyclopedia
Francolite is a carbonate rich variety of the mineral Fluorapatite
and is present in most sedimentary phosphorite
s. It has a variable chemical composition which can be represented by (Ca, Mg, Sr, Na)10(PO4, SO4, CO3)6F2−3. The mineral was named after its occurrence at Wheal Franco, Whitchurch, Tavistock District, Devon, England.
Fluorapatite
Fluorapatite, often with the alternate spelling of fluoroapatite, is a mineral with the formula Ca53F . Fluorapatite is a hard crystalline solid. Although samples can have various color , the pure mineral is colorless as expected for a material lacking transition metals...
and is present in most sedimentary phosphorite
Phosphorite
Phosphorite, phosphate rock or rock phosphate is a non-detrital sedimentary rock which contains high amounts of phosphate bearing minerals. The phosphate content of phosphorite is at least 15 to 20% which is a large enrichment over the typical sedimentary rock content of less than 0.2%...
s. It has a variable chemical composition which can be represented by (Ca, Mg, Sr, Na)10(PO4, SO4, CO3)6F2−3. The mineral was named after its occurrence at Wheal Franco, Whitchurch, Tavistock District, Devon, England.