A Geoscience Digital Image Library

TitlePegmatite containing arsenopyrite, quartz, muscovite and plagioclase from Keystone, South Dakota
DescriptionThis sample is 9 cm across and comes from a pegmatite near Keystone, South Dakota. Most of it is nondescript tan-white plagioclase. Several crystals of semitransparent quartz can be seen on the left hand edge, a book of muscovite is near the bottom. The gray metallic mineral is arsenopyrite. Pegmatites are exceptionally coarse grained igneous rocks that often contain exotic elements and minerals. The pegmatites near Custer have been mined for many years, principally for the lithium they contain.
LocationUSA ▹ South Dakota. Near Keystone.
PhotographerDarla Sondrol. 2001-07-11.
CollectionUniversity of North Dakota Mineralogy Collection #1652.
Key wordsarsenopyrite, quartz, muscovite, plagioclase, South Dakota
Tech details600 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens.
GeoDIL number1128