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This specimen is an example of a mineral that formed in a hydrothermal-metamorphic environment.
Hydrothermal & Metamorphic
The development of a mineral deposit may involve more than one kind of environmental condition. The world-famous and valuable zinc-manganese-iron ore deposit 50 miles northwest of New York, in the Franklin-Sterling Hill area of New Jersey, is an excellent example. About 230 mineral species, a record number, have been found in a complex geologic situation that probably involved both hydrothermal and metamorphic mineral-forming activities.
Franklin, New Jersey