Crystal-chemical features of glauconite from Karinskoe deposit (South Urals)

The results of mineralogical investigation of glauconite from the Karinskoe deposit are presented. Grains were studied using complex of chemical and physical methods: X-ray diffraction, Mцssbauer spectroscopy 57Fe, scanning electron microscopy and microprobe analyses, Fourier-transform infrared spectroscopy. Special attention is given to the crystal-chemical features of mineral and processes of glauconite formation. Glauconite from the Karinskoe deposit is characterized by a relatively high content of K, Fe, Mg. Content of total iron and potassium display a direct correlation. According to Mцssbauer and IR spectroscopy data Fe2+ occupies not more than 10 % of the total iron content in glauconite. Crystal-chemical composition of mineral corresponds to «mature» glauconite, which was formed during the slow «maturing» of glauconite grains with increasing of the mica layers in its structure. Glauconite contains a small (10-15 %) amount of swelling layers. It can be proposed that smectite was a «precursor» for glauconite formation.