WinTtrclas, A Windows program for tetrahedrite group minerals

Abstract

A Microsoft^® Visual Basic software, WinTtrclas, has been developed to calculate the chemical formulae of tetrahedrite group minerals (TGM) based on data obtained from wet-chemical and electron-microprobe analyses. WinTtrclas evaluates currently 40 valid mineral species using the New Minerals, Nomenclature and Classification (CNMMN) of the International Mineralogical Association (IMA–20) nomenclature scheme for the TGM in the general formula ^M(2)A₆^M(1)(B₄C₂)_Σ6^X(3)D₄^S(1)Y₁₂^S(2)Z within the tetrahedrite, tennantite, freibergite, arsenofreibergite, hakite, giraudite, rozhdestvenskayaite, goldfieldite, ústalečite, zvĕstovite and annivite series as well as one unassigned species. Considering occurrence of vacancies at anion sites as well as cation positions in some Te-bearing species, the program provides different estimation and normalization procedures such as the the ΣMe = 32, 29, 27 and 16 atomic per formula unit (apfu),  as well as Σ(As + Sb + Te + Bi) =  4 (apfu) to estimate the chemical formulae of TGM species. Mineral formulae of the tetrahedrite group are calculated based on the dominant cations at the M(1), M(2), X(3) and dominant anions at the S(1)+S(2) sites. WinTtrclas 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 M(1), M(2), X(3) and S(1) sites; (3) it assigns the TGM to one of the eleven series, based on the dominant cations and anions at these sites; and (4) it classifies the TGM species into an appropriate series. WinTtrclas allows users to: (1) enter up to 20 input variables for mineral-chemical analyses; (2) type and load multiple TGM compositions in the data entry section; (3) edit and load the Microsoft^® Excel files used in calculating, classifying, and naming the TGM, 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.