Fine grain verity of Quartz, usually lighter colored, commonly found as nodules in limestone.

A microcrystalline or cryptocrystalline sedimentary rock material composed of SiO2. Occurs as nodules and concretionary masses and less frequently as a layered deposit.

A very fine grained siliceous rock characterized by hardness and conchoidal fracture in dense varieties. The fracture becomes splintery and the hardness decreases in porous varieties. Characteristically shows a variety of colors. Composed of silica in the form of chalcedony, cryptocrystalline or microcrystalline quartz, or opal, or any combinations of these.

a sedimentary rock made of microcrystalline quartz, it forms from the skeletons of microscopic marine organisms

A sedimentary rock composed of granular cryptocrystalline silica.

A hard, dense, mostly quartz sedimentary rock formed by organic or inorganic precipitation or replacement. Chert nodules in Fossil Lake sediments indicate saline, alkaline conditions at the time of their formation.

a hard smooth rock ranging from white to black, also referred to as flint, often found in layers of limestone. This rock, found at Mammoth Cave, was often used for tools and as a fire starter by Native Americans and pioneers.

Hard, dense sedimentary rock, composed of interlocking quartz crystals and possibly amorphous silica (opal); synonymous with flint. Chert makes up about two thirds of the Santa Clara Valley geologic base. close window resize type

A tough, fine-grained silica rock usually found associated with limestone beds.

an extremely fine-grained ("cryptocrystalline") variety of quartz. It foms massive chunks (not crystals), is opaque, and has a white, tan, or beige color

A dense sedimentary rock containing quartz, possibly opal, calcite, and remains of siliceous and other organisms. Ancient seafloor deposits.

is a variety of granular cryptocrystalline quartz, mainly gray coloured.

smooth form of black quartz

Silicon dioxide (SiO2); a compact, massive rock composed of minute particles of quartz and/or chalcedony; it is similar to flint but lighter in color.

Fine grained siliceous rock usually formed in deep sea environments either as a chemical precipitate, or as accumulated remains of siliceous single celled organisms such as radiolaria.

a rock resembling flint and consisting essentially of a large amount of fibrous chalcedony with smaller amounts of cryptocrystalline quartz and amorphous silica Mississippi: A Site for All Seasons

A mainly opaque, fairly granular, silicate rock with a dull shiny luster and a great range of colours, used as raw material for the manufacture of chipped stone artifacts. Varieties include jasper and flint.

Rock composed of precipitated silicon dioxide (microcrystalline quartz, SiO2 ). A common example is flint.

A hard, dense microcrystalline sedimentary rock, consisting chiefly of interlocking microscopic crystals of quartz; occurs principally as nodules in limestone and dolostone.

variety of silica containing microcrystalline quartz

a fine grained sedimentary rock that is white, pinkish, brown, gray or blue-gray in color. It is often shaped into stone artifacts by chipping

need a def Breakage of a micro-crystalline mineral (such as flint or obsidian) into a concave curve

Rock. Hard, amorphous silica found in concretions and beds, often replaces other materials, often reddish or yellowish. Often used by native people to make stone tools.

A hard, dense microcrystaline sedimentary rock, consisting chiefly of interlocking crystals of quartz. It may contain amorphous silica (opal). Chert occurs principally as nodular or concretionary segregations, or nodules, in limestone and dolomite, and less commonly as layered deposits, or bedded chert. The term flint is equally synonymous.

a form of the mineral quartz that has very small crystal sizes. The chemical composition of both chert and quartz is SiO2.

Micro to cryptocrystalline quartz deposits. Chert usually occurs as nodules but may be deposited in layers. Dark gray chert is called flint.

a type of rock or stone, similar to flint, used to make chipped stone tools.

a siliceous rock of chalcedonic of opaline silica occurring in limestone and used in making stone tools

a type of rock; chert can form as a primary deposit preserving fossils within it, or replace organic materials in fossils embedded in different rock material

A member of a group of sedimentary rocks that consist primarily of microscopic silica crystals. Chert may be either organic or inorganic, but the most common forms are inorganic.

(2) -- a form of amorphous silica found in several varieties, e.g. flint (Oxford Dict.)

A hard, extremely dense or compact, dull to semivitreous, sedimentary rock, consisting dominantly of interlocking crystals of quartz; it may contain amorphous silica (opal). It may be white or variously colored gray, green, blue, pink, red, yellow, brown, and black.

Cryptocrystalline silica which may be of organic or inorganic origin. It occurs as bands or layers of nodules in sedimentary rocks.

A very fine-grained sedimentary rock made of quartz. Usually made of millions of globular siliceous skeletons of tiny marine plankton called radiolarians. Black chert is called flint.

Chert - A hard, compact layer of sedimentary rock, commonly called flint.

a rock of various colors, high in silica, commonly found in the Bay Area; breaks with shell-shaped fractures and can be worked into finely made tools.

A variety of microcrystalline quartz. Chert may be almost any color. Black chert is flint. Red chert is jasper. Chert may be disseminated throughout a rock or may be in layers or nodules.

a cryptocrystalline variety of quartz occurs as nodules, lenses or layers in limestone and shales

A very fine grained rock formed in ancient ocean sediments. It often has a semi-glassy finish and is usually white, pinkish, brown, gray, or blue-gray in color. It can be shaped into arrowheads by chipping. It has often been called flint, but true flint is found in chalk deposits and is a distinctive blackish color.

Sedimentary rock. Hard, dense, and chiefly composed of microcrystalline (crystals that can only be seen through a microscope) or cryptocrystalline (crystals too small to be seen with a microscope) quartz. Chert may be the result or organic or inorganic precipitation. Most often, it occurs as nodules in other sedimentary rocks. But it may form in layers, typically referred to as Bedded or Banded Chert, which are commonly formed from the deep-sea deposition of the siliceous skeletons of the microscopic organism Radiolaria.

fine grained form of quartz making up the stream channel bars of Ozark Mountain streams.

A dense, very hard rock composed of microcrystalline silica (varieties also called flint, jasper, agate)

Crypto-Crystaline Silicate. A flint like rock; commonly selected as a raw material for flaked-stone tools.

Hard, dense sedimentary rock, composed of interlocking quartz crystals and possibly amorphous silica (opal). The origin of the silica is normally biological, from diatoms, radiolaria or sponge spicules. Synonymous with flint.

a rock which can be chipped of into pieces with sharp edges

A hard variety of sedimentary rock, similar to flint. It breaks in a predictable fashion which made it highly desirable for prehistoric toolmakers.

Rock type of organic or inorganic origin, occurring as bands or layers in sedimentary rock

An extremely hard, cryptocrystalline quartz rock resembling flint [LCOTE

A sedimentary rock composed of extremely fine-grained quarts, formed by organic or inorganic precipitation or by replacement. Flint and jasper are varieties of chert. Chockstone A rock or boulder wedged into a narrow canyon.

Microcrystalline silica (SiO2).

Chert is a hard, dense, fine-grained type of sedimentary rock, a crystalline aggregate of silica (quartz). It was formed from deposits of silica-based skeletons of microscopic marine organisms (including zooplankton like diatoms, radiolarians, plus sponge spicules and other organic matter). Black chert is called flint.

Chert (IPA: ) is a fine-grained silica-rich cryptocrystalline sedimentary rock that may contain small fossils. It varies greatly in color from white to black, but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements present in the rock, and both red and green are most often related to traces of iron (in its oxidized and reduced forms respectively). Jasper is basically chert which owes its red color to iron(III) inclusions.