The Research Of The Variations Of Chemical Of The Pyrochlore Supergroup Minerals

Pyrochlore supergroup minerals belonging to the broad categories of oxides based on the mineralogical classification, has been studied for more than a hundred years. They are important rare earth oxides for industrial purposes, which are used for extracting niobium, tantalum, uranium and other rare and radioactive elements. But the chemical components of the pyrochlore superfamily are very complex. Studying their components contributes to understand the variation of Nb, Ta and other rare elements.The general chemical formula of pyrochlore superfamily is A2-mB2X6-wY1-n, including various isomorphism replace. In this study, we mainly calculate the chemical formula and make charts to summarize the chemical composition variations of the supergroup, based on self-determination and extensive collection published papers related to the chemical composition data of pyrochlore group minerals in domestic and foreign. We preliminary explore the chemical composition alternative rules of the pyrochlore group(fluornatropyrochlore, calcium fluocalciopyrochlore, fluorkenopyrochlore, "hydroplumbopyrochlore", "Oxynatropyrochlore"), and microlite group minerals.1.In the minerals of fluornatropyrochlore, calcium fluocalciopyrochlore, fluorkenopyrochlore:(a) Position A is often occupied by Na, Ca and the vacancy, and the linear relationship between the apfu(atomic number in the unit molecule) of Na of and the vacancy in the position of A is negative. The relationship displayed as follows: y =-1.0x + 1.0(x is equal to the apfu of Na, and Y is equal to the apfu of the vacancy of position A).(b)The relationship between the apfu of Nb in the position B and F in the position Y is positive.2.In the mineral of "hydroplumbopyrochlore" :(a) The relationship of U-Pb is negative.(b) The relationship of isomorphism of position A and B displayed as follows: 2Nb+Pb ?2Ti+U.3.In the mineral "Oxynatropyrochlore" :The isomorphism relationship of atoms in the position of A and B displayed as follows:Ca+2Nb ?2Ti +U,3Ti+U?3Nb+Na;suggesting the existence of U4+.4.some microlite group mineral(the main composition of position A are Na Ca and vacancy)The relationship between the apfu(atomic number in the unit molecule) of Na of and the vacancy in the position of A is negative.And this agree with fluornatropyrochlore, calcium fluocalciopyrochlore, fluorkenopyrochlore.