Mozarkite is a form of

chert Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a ...

(

flint Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, categorized as the variety of chert that occurs in chalk or marly limestone. Flint was widely used historically to make stone tools and sta ...

). It is the state rock of

Missouri Missouri is a state in the Midwestern region of the United States. Ranking 21st in land area, it is bordered by eight states (tied for the most with Tennessee): Iowa to the north, Illinois, Kentucky and Tennessee to the east, Arkansas t ...

. The name is a

portmanteau A portmanteau word, or portmanteau (, ) is a blend of wordsOzarks The Ozarks, also known as the Ozark Mountains, Ozark Highlands or Ozark Plateau, is a physiographic region in the U.S. states of Missouri, Arkansas, Oklahoma and the extreme southeastern corner of Kansas. The Ozarks cover a significant port ...

), and ''ite'' (meaning rock). Mozarkite consists essentially of

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...

(

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

- SiO₂) with varying amounts of

chalcedony Chalcedony ( , or ) is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monocli ...

. It has won distinction as a particular form or variety of chert because of its unique variation of colors and its ability to take a high polish. It has the hardness of 7-7.5 on the Mohs scale, which qualifies it as a suitable material for semi-precious gemstone, and has a density of about 2.65 g/cm³. Typically, the colors are different hues of red, pink, and purple with varying tints of green, gray and brown. It is collected and admired by lapidarists across the country. Interest in collecting mozarkite in Missouri started in the early 1950s, in

Benton County, Missouri Benton County is a county located in the west central part of the U.S. state of Missouri. The population was 19,394 as of the 2020 Census. Its county seat is Warsaw. The county was organized January 3, 1835, and named for U.S. Senator Thomas ...

. It is found primarily in west-central Missouri, south of the Missouri River, and west of the

Lake of the Ozarks Lake of the Ozarks is a reservoir created by impounding the Osage River in the northern part of the Ozarks in central Missouri. Parts of three smaller tributaries to the Osage are included in the impoundment: the Niangua River, Grandglaize Cr ...

. Mozarkite occurs in the Cotter Dolomite of

Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. T ...

age, which means it is some 450 million years old. It is found in residual boulders in the soil on hill slopes, along ditches, and in roadcuts where the boulders are exposed in the soil formed by weathering of the Cotter Dolomite.

State Rock

* Mozarkite was designated the official state rock of Missouri by the 74th

Missouri General Assembly The Missouri General Assembly is the state legislature of the U.S. state of Missouri. The bicameral General Assembly is composed of a 34-member Senate and a 163-member House of Representatives. Members of both houses of the General Assembly are ...

in 1967.

References

*Missouri Department of Natural Resources, Geological Survey and Resource Assessment Division fact sheet number 23; PUB 000653; 6/2002 {{Silica minerals Chert Lithics Symbols of Missouri Quartz gemstones