Comparison of the number of analyses required for reproducible bulk compositional data as a function of the scale of sample to measurement heterogeneity (upper). The same plot is used to indicate where various analytical techniques and common geological samples might intersect (lower). STEM-EELS—scanning transmission electron microscopy–electron energy loss spectroscopy; XAS—X-ray absorption spectroscopy; LIBS—laser-induced breakdown spectroscopy; EPMA—electron probe microanalysis.