Carbon and oxygen isotope composition, geochemistry, and petrography of carbonate minerals in the Mountain Pass carbonatite (ver. 1.1, February 2026)

This data release contains in situ carbon and oxygen isotope analyses of calcite and dolomite collected via secondary ion mass spectrometry (SIMS), as well as major and trace element geochemical data, bulk mineral carbon and oxygen isotope data, and whole rock geochemistry for the samples included in this study. Also included are images from analyzed thin sections that show the sample locations in backscattered electron (BSE), hyperspectral cathodoluminescence (CL) and element maps.