ARMADILLO_VolcaNorm: An open-source, macro-enabled VBA for Excel™ spreadsheet for calculation of CIPW norms and IUGS igneous rock classification for volcanic rocks

ARMADILLO_VolcaNorm is a versatile, user-friendly, open-source, macro-enabled spreadsheet that can rapidly calculate CIPW normative mineralogy (viz., "a norm") and classify volcanic rocks following IUGS recommendations entirely within the Microsoft ExcelTM environment. The program can process up to 10,000 major-element analyses of volcanic rocks, with the user specifying whether total iron is reported as FeO* or Fe2O3* and selecting one of seven methods of re-partitioning iron (or providing a custom value), including options that incorporate temperature, pressure, redox buffer, and offset. ARMADILLO_VolcaNorm outputs the FeO/FeO* ratio for each sample, computes the normative mineralogy, and applies total alkali-silica (TAS) and norm-based criteria for accurate classification. It can also generate customizable TAS diagrams with labeled samples. Unlike previous tools, ARMADILLO_VolcaNorm operates seamlessly within Excel, enabling simple copy-and-paste workflows and enhancing reproducibility and accessibility in igneous petrology.