Primary minerals deposited by hydrothermal fluids include pyrite, marcasite, galena, chalcopyrite, bornite, sphalerite, anhydrite, quartz, and goyazite. Secondary minerals include base metal carbonates, chalcocite, covellite, beudantite, and various oxides. The presence of other primary sulfate minerals, the lack of any local source of potassium and the absence of samples clearly indicating a secondary weathering relationship of sulfide to jarosite suggests that some of the jarosite may be hydrothermal in origin. Thermodynamic stability of jarosite permit the formation of hypogene jarosite for the postulated conditions of Apex hydrothermal mineralization.
Exceptions are pyrite, which is low in germanium, and sphalerite, which is low in both elements.
C oexisting liquid and vapor homogenization fluid inclusions indicate boiling. E nrichment of gallium in galena and relative depletion of gallium in other sulfides, along with petrographic evidence, suggests that galena may have been deposited in a later stage on primary mineralization. Gallium-beudantite is probably a product of secondary weathering and enrichment of this galena. The probable source rocks for Apex germanium and gallium are the cambrian Bright Angel shale and the precambrian basement metamorphics. New Mexico Tech.