Chromium three-isotope plot showing the line defined by mass-dependent variations (top). ⁵⁴Cr-excesses relative to this line cannot be explained by any physico-chemical processes and thus correspond a mass-independent anomaly. Bottom: Same but for the oxygen three-isotope plot. Terrestrial rocks all plot along a 1/2 slope line passing through (0,0), called terrestrial fractionation line (TFL). Again, any deviation from this line corresponds to an mass-independent anomaly. The plot also shows the composition of the Sun, of refractory inclusions (CAIs and AOAs) and chondrules, which are all anomalous with respect to Earth. Note: meteorites and chondritic constituents lay along a line of slope ∼1, dubbed the primitive chondrule minerals (PCM) line, Ushikubo et al. (2012).