Red, Yellow and Black Quicksilver Minerals

MANY producers have held that the only workable quicksilver ore is easily recognized by its .cinnabar content. In most cases this is true. A noticeable exception is a. particular opalite deposit where part of the ore now being mined in considerable quantity shows only the yellow mineral, calomel, or its alteration products. This mineral, on exposure to the sunlight, quickly becomes coated with gray or black layers that may be removed by scraping to reveal the yellow mineral beneath. The blackening of this mercuric chloride on exposure to sunlight shows reaction to form metallic mercury, which is usually plainly present in this class of ore.