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Part of Hall of Planet Earth.
AMNH/R.Mickens
This granite pegmatite illustrates the growth of extremely large crystals from a magma. It is composed of large feldspar (white) and biotite mica (silver-black) crystals in a groundmass of small crystals of quartz (gray), microcline, and albite (both white).
Provided by the Feldspar Corporations, Spruce Pine, North Carolina