This display case exhibits some fine examples of pegmatite minerals
collected from New York State.
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Pegmatite Minerals of New York
Pegmatites are bodies of unusually coarse-grained rock formed
deep in the crust of the Earth. They precipitated from a fluid phase separated from
the residual granitic melt in the final stages of the solidification of magma.
Generally, pegmatites have a granitic composition and occur as dikes, lenses or veins.
Most of their minerals are more than 1 cm in diameter, but individual crystals can
reach tens of meters in length. Simple pegmatites contain albite, quartz, microcline
and possible minor muscovite. Complex pegmatites carry rare minerals such as columbite,
beryl, zircon, monazite, polycrase and uraninite.
The major pegmatites of New York occur primarily in Westchester, Saratoga, Warren
and Essex Counties. They were an important industrial source of feldspar for
ceramics and mica for insulators and also provided rare elements such as niobium,
beryllium, and uranium for high tech industries.
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