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
Carbonate-hosted lead-zinc ore deposits brines (10-30 wt.% NaCl equivalent) with pH's of 4.5-5 (buffered by host carbonates). This hydrothermal fluid may or may not carry the required sulfur to form sulfide minerals. Mobile hydrocarbons may have played a role in delivering reduced sulfur to certain MVT systems, while methane and other organic matter can potentially reduce sulfate carried by an acidic fluid. The ore fluid is suspected to be derived from clastic red bed sequences (potential metal source) that contain evaporites (potential sulfur source). Two potential transportation mechanisms for the metal-bearing ore fluid have been proposed. The first involves compaction of sediments in basins