North America is host to a wealth of natural materials that inhabitants have used to create gleaming jewels and ornaments for thousands of years. Various minerals originating among the geology of Kansas have semi-precious status, thanks to the crystals they exhibit and the lucidity of their colors. Cut and polished, such stones become highly salable assets.
The kimberlite rocks of Riley and Marshall counties in Kansas are igneous in nature. This gray rock originates deep in the upper mantle of the earth. As it erupts it expands and breaks through the crust to form pipes in small clusters. The explosion forms small craters at the surface that deposit a mixture of igneous and sedimentary rock. Garnets, dark red semi-precious stones with many faceted crystals and a glassy luster, often form within the mix. Stores across Kansas sell these smooth, polished garnets.
"Chalcedony" is a term for a family of gemstones which are cryptocrystalline in texture, meaning they are comprised of minute crystals. It includes minerals such as chert and flint, which exhibit several different colors. In Kansas chalcedony is present within geodes, or crystal-lined cavities in rocks. They form when minerals in ground water deposit themselves in solution on the walls of rock cavities. Geodes which contain chalcedony are present in Riley, Marshall and Chase counties and in various places in the Flint Hills.
Marcasite is a brittle secondary mineral related to pyrite that forms due to chemical alteration of certain primary minerals. It occurs in Kansas as concretions and crystals in coal, shale and limestone. It is usually a pale yellow, but sometimes appears white and has a bright metallic luster. In Cherokee County crystals have appeared in the lead and zinc mines of the Tri-State district; they are present in all the coal mines of southeastern Kansas.
Sphalerite, or zincblende, is the major ore of zinc. This transparent mineral is present in the Tri-State district of Cherokee County in Kansas. In its purest form it develops crystals of colors from pale yellow to red. With greater iron content the crystals become darker in color and more opaque.