Even an occasional clean micro-sphalerite crystal was seen. Thick botryoidal fluorescent blue-white calcite coatings were mistaken by many collectors for smithsonite. An adjacent portal that opened into a large natural cave system produced stubby quartz crystals on chert matrix that sometimes contain included chalcopyrite. The Monte Cristo was the last active mine in the district, having closed in 1962. The other mine, privately owned, that produced many specimens was the Philadelphia.
Present ownership is in question.
In the early 1960's, a collector- dealer got permission to mine specimens and many spectacular yellow dolomite crystals on druzy quartz matrix were available for collectors. These specimens resulted from the partial replacement of the typical pink dolomite by tiny yellow smithsonite crystals. In the 1980's many specimens of smithsonite were recovered by collectors. The backs of both adits reached into the unweathered zones of mineralization, a primary dolomite-coated chert breccia. In pockets in the breccia, fresh mineralization could be seen, but not so easily extracted.