origin of graph...
This is from:
APXS on Mars: Analyses of soils and rocks at Gusev Crater and Meridiani Planum, Rieder, R. et. al. about the similarity of soils on the two landing sites.
I redrew it to make a point. I guessed on the y axis value for sulfur, being larger than the soil, not so large on the log scale as to be stupid, but enough to be remarkable. Guess I over shot. What else do I got? Gimme the damn graph.