Minium (pigment) Minium (pigment) Minium, also known as red lead, is a bright orange red pigment that was widely used in the Middle Ages for the decoration of manuscripts and for painting. It was made by roasting white lead pigment in the air; the white lead would gradually turn yellow, then into an orange lead tetroxide. The color varied depending upon how long the mineral was roasted. During the Roman Empire, the term minium could refer either to the pigment made from ground cinnabar or to the less expensive red lead. The name came from the river Minius in Iberia (now forming
Labrador Retriever coat colour genetics the colour of the dark pigment, eumelanin, and is referred to as the B (brown) locus. The variation displayed by this locus is observed in many mammals, reflecting a so-called 'dilution', a lightening, of black eumelanin to a brown colour. Initial genetic research excluded a role for the melanocortin 1 receptor and the "Agouti" locus as being the cause of the black dilution trait in dogs. Instead, TYRP1 (tyrosine related protein 1) was found to be responsible. This enzyme is localised to melanosomes, the cellular organelles that produce and store pigments, and serves to catalyze oxidation of eumelanin precursors. In