“Out, damn'd spot!” — Lady Macbeth. As we at JSR PaperClips continue our celebration of 400th anniversary of the Bard’s demise, we recall another famous stained contribution—that of Tony Dickson, who 50 years ago pointed out how staining of carbonate rocks with alizarin red-S and potassium ferricyanide can aide in differentiation of orthorhombic carbonates (such as aragonite), trigonal carbonates (such as calcite), and iron-rich calcite and dolomite. So, with clear conscience and citing little risk, we recommend re-reading this classic.
Carbonate identification and genesis as revealed by staining by J.A.D. Dickson