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lin murphy
Jan 24, 2009
Weathering in the Colorado Mineral Belt near Boulder. These rocks have been chemically changed by the circulation of hot fluids rising up along very old faults. While hydrothermal alteration has basically destroyed these rocks from a climbing point of view, other hot-fluid alteration (Adularia:potassium feldspar) accounts for the hard sandstone of the Fountain Formation in El Dorado Canyon. See scanning electron microscope pic of this adularia, infra. Fountain Formation rocks that are not near the Colorado Mineral Belt are poorly cemented and crumbly.  


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