From their web page: "Igor is an extraordinarily powerful and extensible scientific graphing, data analysis, image processing and programming software tool for scientists and engineers. (2005) Petrograph: a New Software to Visualize, Model, and Present Geochemical Data in Igneous Petrology, Geochem.
Source code is written in MS Visual Basic 6.0 and it runs under Windows 98/2000/XP platforms. Possible to plot many classification diagrams and "petro-tectonic" plots. Petrograph - Free software that is user friendly.Announced as a package for Igneous Petrology but can be generalized to plot any other kind of plots." Informative website, and short learning time. Interpretation of whole-rock geochemical data in igneous geochemistry: introducing Geochemical Data Toolkit (GCDkit). Details can be found in: Janoušek, V., Farrow, C. (a computer language for statistical computing and graphics). Compatible with Excel, which makes it easy to manipulate data and calculate things with formulas. If you select a point or cluster of points on a plot, it is highlighted in the spreadsheet. Templates for various kinds of plots (ternary, spider diagrams etc.) available.
NOTE: If you have Excel spreadsheets set up to do geochemical plotting, please send the files to Dave Mogk (mail to: mogk AT ) for posting on this list. Can be used with mineral data as well, but fewer built in diagrams. Can do basic modeling such as melting, fractionation, AFC.
Diagrams can be exported to most drawing programs, such as Corel, for "prettying up". Most "canned plots" or "stock diagrams" can be generated. Spider diagrams include REES, Wood, Thompson, Sun and McDonough etc.). CMAS projections include O'Hara, Walker, Grove, Baker and Eggler etc. the Irvine and Baragar (1971) rock classification scheme, are stored in control files that can be expanded easily. A calculator includes (+ - / *), Log, square, square root, ppm and chondrite functions.