Two general types of deposits are recognized in the Corocoro basin--deposits in channel-type depressions containing up to a few percent chalcocite, replacing fossil plant remains; deposits in structural highs, which may be either native copper (grades up to 5 or 10 percent) in reddish sandstones or chalcocite (up to 10 or 20 percent) in grayish sandstones. With the exception of subordinate fracture fillings, the ores are strata-bound and occur in sandstone rather than shale. The lower-grade channel-type deposits are interpreted as syngenetic; redistribution of this copper gave rise to the richer tectonically controlled deposits.

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