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Widely distributed deposits of copper ("Red Beds" type), vanadium-uranium and silver, occurring in sandstones and shales of Permian, Triassic and Jurassic age, exhibit many common features and are thought to have had a similar origin. Mineralization, although mostly discontinuous, is recurrent at certain stratigraphic horizons. Commonly the ore bodies are distinctly lenticular and in some cases it can be demonstrated that mineralization was restricted to a particular lens. Chalcocite pseudomorphs after plant fossils show undeformed cell structure, suggesting mineralization previous to deep burial. Geologic structures, such as faults and folds appear to be post-mineralization and show no genetic relationship to ore deposition. This evidence opposes current ideas of mineralization by circulating meteoric waters or ascending thermal solutions, and it is believed that the concentration of the metals occurred at the time of deposition of the enclosing sediments. It is suggested that these metals may have been concentrated from dilute solutions by organisms. CONTENTS.

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