Mercury Ore

any of the natural mineral formations containing mercury in concentrations such that the industrial use of the minerals is both technically and economically warranted. The most important mineral of the mercury ores is cinnabar, HgS, with a mercury content of 86.2 percent. Secondary minerals include metacinnabarite (β-sulfide of mercury), native mercury (Hg), livingstonite (HgSb₄S₇), corderoite (Hg₃S₂Cl₂), and the mercury-containing sulfosalts of Cu, Sb, and As. Distinctions are made between high-grade mercury ores (approximately 1 percent Hg), medium-grade ores (0.2–0.3 percent Hg), low-grade ores (0.06–0.12 percent Hg), and very low-grade ores (0.02–0.06 percent Hg). Complex mercury ores contain Sb, Cu-Pb-Zn, W, Au-Ag, and the harmful admixture As.

The ore bodies are flat sheets, contact deposits, veins, pockets, and stockworks with a volume from several cubic meters to hundreds of thousands of cubic meters. Mercury ores are usually formed by low-temperature, dilute (3–5 grams per liter) hydrothermal solutions having the temperatures 250°–100°C, and, less often, by superheated gas-liquid emanations saturated with mercury vapor. In this regard, distinctions are made between hydrothermal, telethermal, and volcanic mercury ores.

Telethermal deposits have the greatest industrial importance and include conformable accumulations in dolomites, limestone, and quartziferous sandstone found under schistose rocks. These deposits are found in the Donbas, Northern Caucasus, Yakutia, and Chukchi National Okrug in the USSR and in Almadén in Spain. They also exist as ore shoots in zones of listvenitization (Middle Asia, Altai Krai, and Transcaucasia in the USSR and New Almaden in the USA) at the contact of ser-pentinites with slates. Volcanic deposits exist as mantlelike deposits in effusive and sedimentary rocks (Kamchatka in the USSR and Sulfur Bank in the USA). While volcanic deposits are worked by open-pit mining, the other types of deposits must be worked primarily in underground mines. Mercury is sublimated in rotary kilns and fluidized bed furnaces without prior concentration of the ores.

The overall reserves of mercury ores are estimated at 500,000 tons. The annual production in capitalist and developing countries was 7,000–8,000 tons in the period 1968–73, including 1,500–2,000 tons produced at Almadén in Spain and the Amiata mountain in Italy. Deposits in the USA, Canada, and Mexico yield from 500 to 1,000 tons annually, those in Turkey, Algeria, and Japan yield from 100 to 300, and the deposits in Peru, Chile, and Tunisia account for 10 to 100 tons per year.