Phosphorite is a sedimentary rock with a high enough content of phosphate minerals to bo of economic Interest. Most phosphorites are composed predominantly of m1crocrystall1no to cryptocrystalline carbonate fluorapatlte thenceforth In this report referred to simply by the mineral group name apatite). Florida produces roughly 1/3 of the world's supply of phosphate rock, most of which is used 1n the fe rtiliz e r Industry.

Long term continuation of phosphorite mining In Florida will require exploitation of the extensive hlgh-magneslum phosphorite deposits south of the present mining d istrict 1n central Florida, and this will require new technology In order to produce beneficlated concentrates with less than 1% MgO, a limit Imposed by fe r tiliz e r processing technology. In order to develop benefication methods applicable to these ores, it is essential to know how Mg occurs in phosphorites. Dolomite, CaMg(C03)2, is the chief host of Mg In phosphorites from Florida. Magnesium may also be present, however, as a substituent In apatite (the chief phosphate.mineral in these deposits), as a minor substituent 1n calcite (CaCO3), in certain clay minerals (particularly palygorskite and to a lesser extent in some smectites), and/or in organic matter within the apatite particles.