Yellow colours:  Often pure sulphur (The Krysuvik Area).

Red and brown colours:  Iron and sulphur (Fe, S), which assimilates with the oxygen of the atmosphere.  The sulphur creates yellow colours and the iron red and brown hematite.

Grey colours:  are created when sulphuric acids dissolve the basaltic rock.  H2S assimilates the oxygen of the ground water and creates H2SO4 and clay minerals are created.

Light colours:  are mainly created by Silica (SiO2), Calcium (CaCO3), and sometimes also Gypsum (CaSO4, H2O).