![]() Ancient Knapping in ActionĬonchoidal fracturing is the mechanical basis of flaking or knapping, a Paleolithic skill and an art that survives among flint knappers today. This “steers” the developing fracture back toward the surface, displacing a thin flake of flint and leaving behind a conchoidal depression. Fracturing absorbs part of the shockwave energy which, as it decreases, exerts its greatest pressure in the direction of least resistance. Within microseconds, this fracturing and energy progress through the flint at an angle slightly declined from the surface. When flint is struck by an edged or pointed object, fracturing and an accompanying shockwave of mechanical energy begin at the point of impact. The word “conchoidal” itself stems from the Greek konchoeids, meaning “like a mussel”. Conchoidal fractures appear as smoothly curving, concave breaks that are generally similar in shape to the inner surfaces of bivalve mollusk shells. A collection of Flint Ridge flint arrowheads Conchoidal Fractureįlint’s most notable property is its conchoidal fracture, which is diagnostic in all types of quartz. Along with chalcedony, flint also contains small amounts of water, calcite, carbon, various iron and manganese oxides and hydroxides, and the opal-like mineral mogánite (hydrous silicon dioxide, SiO2♳H2O).Īs a product of the solidification of silica-rich solutions or the alteration of silica-rich materials, flint forms through one or a combination of three processes: compaction and crystallization of microscopic, siliceous skeletal structures precipitation of silica from seawater or the replacement of calcite in limestone by silica in groundwater. It resists erosion and can occur in a wide spectrum of colors. Tough, Durable, and ColorfulĪs a high-silica, chemical-sedimentary rock, flint is dense, tough, durable, fine-grained, and quite hard (Mohs 7). Knappers take advantage of this property to shape tools from the flint. It also exhibits a better-defined conchoidal fracture that lends itself to flaking. ![]() ![]() Flint is generally considered a finer-grained, more homogenous, and somewhat harder type of chert. Both occur as nodules or layers within formations of limestone, dolomite or chalk. The terms “flint” and “chert” overlap and are sometimes used interchangeably. Because of their variable chemical compositions, they are classified as rocks. While agate and jasper are almost pure chalcedony, chert and flint are impure forms. Chalcedony’s other subvarieties are agate, jasper and chert. About Flintįlint is a type of chalcedony, the microcrystalline variety of quartz. Pin this post to save this information for later. Attractions include a museum with informative flint-related exhibits, trails leading to hundreds of prehistoric flint quarries, two annual flint-knapping events, and a nearby fee-collecting site, where rockhounds can collect their own colorful specimens of Flint Ridge flint. As a source of high-quality flint, Flint Ridge began attracting Native Americans some 12,000 years ago and is still drawing people today.įlint Ridge is the site of the Flint Ridge State Memorial and the Flint Ridge Ancient Quarries and Nature Preserve. While the topography of Flint Ridge may be unremarkable, that’s not the case with its cultural significance. Rolling Countryside With Unique Geologyįlint Ridge, located in southeast Ohio about 40 miles east of Columbus, the state capital, is an unimposing, low escarpment in the gently rolling farm country just north of Interstate 70. Along with a fascinating history and geology, it’s no wonder that Flint Ridge flint with its rainbow of colors and ability to take a superb polish is also Ohio’s official state gemstone. (Photo by Tim Jordan)įlint from Flint Ridge, Ohio, is prized by flintknappers, lapidaries, jewelry makers, and mineral collectors. These flint preforms show the rough shape of the point that is being knapped.
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