The geology of the Montgomery Creek mining district and the R & S Mine area, Benton Quadrangle, California-Nevada

Abstract

Marble, quartzite, and interbedded calc-silicate hornfels of the Cambrian age Poleta is exposed in the Benton 15' quadrangle. Recrystallized calcite with minor amounts of magnetite, hornblende, biotite, and limonite are the usual minerals present in the marble. Metasomatism introduces large amounts of limonite, chlorite, sericite, lead, and silver in bedded replacements and fissures of quartz-calcite, in fractures within propylitically altered rocks and in jasperoid breccia. Intrusion of quartz monzonite has suspended the carbonate as roof pendants atop the plutonic rocks. Garnet skarn has developed locally along intrusive contacts. Uranium values above background occur in pegmatites and calc-silicate hornfels in the White Mountains and in pumiceous rhyolite tuff in the Benton Range. Additional sulphide mineralization may extend beneath volcanics in the Benton Range and beneath zones of alteration in the White Mountains.