Search results
Results from the WOW.Com Content Network
Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, [1] [2] categorized as the variety of chert that occurs in chalk or marly limestone. Historically, flint was widely used to make stone tools and start fires. Flint occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones.
Chert (/ tʃ ɜːr t /) is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, [1] the mineral form of silicon dioxide (SiO 2). [2] Chert is characteristically of biological origin, but may also occur inorganically as a chemical precipitate or a diagenetic replacement, as in petrified wood.
Flint and chert are the most commonly knapped materials and are compact cryptocrystalline quartz. The difference between the two terms is colloquial , and flint can be seen as a variety of chert. In common usage, flint may refer more often to high quality material from chalky matrix (i.e. "chalk flint" as found in Britain) and chert refers to ...
Chert and flint nodules are often found in beds of limestone and chalk. They form from the redeposition of amorphous silica arising from the dissolution of siliceous spicules of sponges, or debris from radiolaria and the postdepositional replacement of either the enclosing limestone or chalk by this silica. [2]
Among the sedimentary rocks, chert and flint are cryptocrystalline. Carbonado, a form of diamond, is also cryptocrystalline. Volcanic rocks, especially of the felsic type such as felsites and rhyolites, may have a cryptocrystalline groundmass as distinguished from pure obsidian (felsic) or tachylyte (mafic), which are natural rock glasses.
The notched version was probably hafted as a spade. Another advantageous property of the Mill Creek chert was the large size of the nodules, which meant that the corresponding tools could be large. Some hoes were up to 60 centimetres (24 in) in length. [4] The other main use for the chert was large ceremonial bifaces, spatulate celts and stone ...
Main article: Flint. A hard, sedimentary cryptocrystalline form of the mineral quartz, [14] [15] categorized as a variety of chert. It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones. [16] [17] Inside the nodule, flint is usually dark grey, black, green, white, or brown in color, and often has a glassy ...
Cryptocrystalline or amorphous stone such as chert, flint, obsidian, and chalcedony, as well as other fine-grained stone material, such as rhyolite, felsite, and quartzite, were used as a source material for producing stone tools.