Cinnabar is a vivid red, highly toxic ore and the principal material refined into quicksilver. Its colour also makes finely ground cinnabar valuable as a pigment for strong red paints, but the same material that produces the colour makes careless handling dangerous.
Uncovered skin contact causes poison harm with sustained exposure, and heating or crushing the ore can spread hazardous dust and fumes. Miners, alchemists and pigment makers therefore use gloves, covered containers and well-ventilated workspaces. Bright colour is not a sign that a specimen is safe; it is the easiest warning that it is not.