WinPclclas, a Windows Program for Pyrochlore Supergroup Minerals

Abstract

Abstract A Microsoft® Visual Basic program, WinPclclas, has been developed to calculate the chemical formulae of pyrochlore supergroup minerals (PSM) based on data obtained from wet-chemical and electron-microprobe analyses. These are also classified following the nomenclature scheme adopted by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association for PSM (IMA-10) and including both subsequent group and species updates. The program considers classification among the 33 IMA-approved PSM, as well as ten species that have not been approved, adhering to the general formula A2B2X6Y and considering the dominant ions at the A, B, and Y sites. It considers PSM represented by the pyrochlore, microlite, roméite, elsmoreite, and betafite groups, along with unassigned members of the ralstonite and coulsellite groups. Mineral formulae of the PSM are calculated based on the ideal number of B cations being two apfu, owing to the potential for vacancies at the A, X, and Y sites. WinPclclas operates in four stages: (1) it estimates cation and anion contents provided by input chemical data; (2) it determines the dominant cation and anion at the A, B, and Y sites; (3) it assigns the PSM to one of the seven groups, based on the dominant cation at the B site (i.e., W6+, Nb5+, Ta5+, Sb5+, Ti4+, Al3+, and Mg2+); and (4) it classifies the pyrochlore species into an appropriate group, based on the dominant cation at the A site and the dominant anion at the Y site. The H2O (wt.%) content for the PSM is estimated by stoichiometric constraints. WinPclclas allows users to: (1) enter up to 51 input variables for mineral-chemical analyses; (2) type and load multiple PSM compositions in the data entry section; (3) edit and load the Microsoft® Excel files used in calculating, classifying, and naming the PSM, together with the total monovalent to hexavalent cation, and (4) store all the calculated parameters in the output of a Microsoft® Excel file for further data evaluations. The program is distributed as a self-extracting setup file, including the necessary support files used by the program, a help file, and representative sample data files.