Reddle, RADDLE, or RED CHALK

Reddle, RADDLE, or RED CHALK (Scot. keel), an impure peroxide of iron (ferric oxide) associated with very variable proportions of clay or chalk, or sometimes other substances. It varies greatly too in hardness, some kinds being difficult to crush and others quite soft. In colour it passes from a pale brick-red to a tint occasionally nearly as bright as vermilion. It is found in many places abroad, and in England in Somersetshire, the Forest of Dean, at Wastwater in Cumberland, and, of a quality valuable for polishing optical glasses, near Rotherham in Yorkshire. Some kinds of it are used for marking sheep, others for carpenters' and masons' pencils, and the finer qualities for artists' crayons. Red ochre is one of the varieties.