Geothermometric investigations on ores from the magma mine, Superior, Arizona

Heating experiments on ore samples were conducted to determine the temperatures and conditions of formation. The samples were heated in evacuated, sealed silica tubes for times ranging from 48 to 120 hours at temperatures ranging from 200'to 550**C. Microscopic and x-ray examination of heated and unheated samples revealed little change in mineralogy. Geothermometric application of the assemblages studied is of little significance at the present time. Idaite was identified in the Magma samples. The use of invariant points and univariant sulfidation reactions as well as S2 fugacity calculations are presented as a means of establishing order of magnitude limits on conditions of ore formation. A brief review of geologic and mining work is also presented.