State by State
- Specimen Number
Irregular boulder of complex rock that is likely a coarse igneous protolith with phenocrysts and pervasive hydrothermal alteration. Identified by staff from the State Geological Survey. Malachite stain on rim suggests bulk rock is metalliferous. It's possible the metal crystals were visible when the sample was collected, but have since oxidized.
Complex. Hydrothermally altered protolith. Ore. Silver.
- Location & Occurrence
Malachite and rust indicate likely ore from silver mines in southwestern state near Phillipsberg, confirming the Hartford Courant identification as "silver-bearing ore." The Connecticut Campus identified it as having come from Iowa.
- Geologic Age
Likely of Mesozoic age (synorogenic). Protolith and alteration have different ages.
Sample of Cordilleran ore illuminates the story of western mining.
Mentioned as "silver-bearing ore" in Hartford Courant 1937, confirming informants speculation of location.