Mercury (element) long periods at elevated temperatures. It reverts to the elements upon heating near 400 °C, as was demonstrated by Joseph Priestley in an early synthesis of pure oxygen. Hydroxides of mercury are poorly characterized, as they are for its neighbors gold and silver. Being a soft metal, mercury forms very stable derivatives with the heavier chalcogens. Preeminent is mercury(II) sulfide, HgS, which occurs in nature as the ore cinnabar and is the brilliant pigment vermillion. Like ZnS, HgS crystallizes in two forms, the reddish cubic form and the black zinc blende form. The latter sometimes occurs naturally as metacinnabar. Mercury(II)
Browns polymetallic ore deposit "sulfide" resources. The oxide resources consist of supergene or weathered sulfide ore where the ore mineralogy is dominated by metal oxides, hydroxides, clays and carbonates after the original sulfide mineralogy. The Browns deposit is currently being developed as a major base metals mine by Compass Resources NL, an Australian public company, in joint venture with Hunan Nonferrous Metals Corporation, a Chinese government company. The mine is due to be complete in August 2008, after suffering cost escalation and construction delays, and will produce 15,000 tonnes of copper, 4,000 tonnes of cobalt and 4,000 tonnes of nickel per annum, with a