An introduction to Franklin minerals

Overview

Franklin minerals are those minerals found in the Franklin and Sterling Hill mining district, located in the northwestern corner of the State of New Jersey, and include some of the most peculiar species on earth.

	A polished thick-section of unusual Franklin ore: zincite (red), franklinite (black), and the rare mineral manganosite (green). Width 2 cm.

This district contains two large and very unusual orebodies of zinc-manganese-iron.

Located a few miles apart, they have been worked for over 150 years; one on Mine Hill in the town of Franklin, and the other on Sterling Hill in the town of Ogdensburg. The two deposits are closely related, and share much of the same peculiar mineralization.

Together, they form a unique type of mineral deposit : no other similar mineral deposit has ever been found anywhere else in the world.

More than 340 minerals, some 80 of them fluorescent under ultraviolet light, are known from the Franklin-Sterling district -- a world's record.

	Franklin fluorescence: close-up view of esperite (yellow), willemite (green), and calcite (red) fluorescing brightly under shortwave UV. Width 4 cm.

The formal boundaries of the 'Franklin-Sterling Hill district', as it is referred to today, are based on guidelines established by Dr. Pete J. Dunn and Mr. Jack Baum recommended and first published in The Picking Table, the journal of the Franklin-Ogdensburg Mineralogical Society.

If you are not familiar with Franklin minerals, check out our fluorescence gallery or SEM/ micro gallery to find out more.

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