Chert is among the most diverse sedimentary rocks, taking on various colors and forms. It also comes in wide varieties, such as flint, mozarkite, bedded chert, …In geological terms flint and chert are the same, with the term “flint” referring to chert found in chalk. Cherts are formed in limestone. Both archaeologists ...In 1953, the late Stanley Tyler, a geologist at the university who passed away in 1963 at the age of 57, was the first person to discover microfossils in Precambrian rocks. This pushed the origins of life back more than a billion years, from 540 million to 1.8 billion years ago. “People are really interested in when life on Earth first ...Feb 9, 2023 · The chert rock is a typical and intrinsic by-product in the quarrying of sand in the Mishor-Rotem region (Figure 3a).This is dark, stripped, highly abrasive, and strong gravel (Figure 3b) of rock, sometimes covered with white carbonate material. Jun 4, 2021 · Basically, chert is a petrified limestone rock where the calcium carbonate is displaced with silicon dioxide. The limestone rocks found in the Ozarks formed in a shallow tropical sea much like we have in the Caribbean today. Most of the Ozarkian chert deposits are in Mississippian-age deposits, from about 325 to 360 million years ago. On the rocks cocktails have been a popular drink choice for many years, but their origins can be traced back to the early 1800s. This classic cocktail is typically made by pouring spirits over ice and garnishing with a slice of citrus or ot...Get the best deals on Flint Rock when you shop the largest online selection at eBay.com. Free shipping on many items | Browse your favorite brands ...8+ POUNDS Central Texas “Edwards Plateau”Chert/Flint Rocks for Knapping/Lapidary. $25.00. $8.50 shipping. 3 POUNDS!! USA Ozark CHERT FLINT LARGE PIECES rough stone rock PRIMITIVE FIRE. $19.95. Free shipping. or Best Offer.Chert is a hard, fine-grained sedimentary rock composed of microcrystalline crystals of quartz, the mineral form of silicon dioxide. Chert is characteristically ...Rocks and minerals can be easily identified once you know what to look for. There are three different types of rocks: Igneous, Metamorphic and Sedimentary. Minerals must meet several requirements, including being naturally occurring and ino...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. Flint was widely used historically to make stone tools and start fires . Flint occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones.The chert-based Kaibab and BIF rocks containing calcium and magnesium-carbonate and iron oxides constitute just a few chert minerals commonly found in Arizona and are now known worldwide. These mineralized rocks establish the complex of chert formations that encompass Earth’s fundamental stratigraphic units as defined by the …Feb 9, 2023 · The chert rock is a typical and intrinsic by-product in the quarrying of sand in the Mishor-Rotem region (Figure 3a).This is dark, stripped, highly abrasive, and strong gravel (Figure 3b) of rock, sometimes covered with white carbonate material. Cherts are tough, compact rocks with low porosity that are composed mainly of microcrystalline quartz and varying amounts of impurities (Folk et al 1952; Smith 1960). …Chert is a sedimentary rock rich in silica. Franciscan chert is formed from the tiny silica shells (0.5-1 mm) of marine plankton called Radiolaria. Radiolarian chert forms where two conditions are met. First, a deep, open ocean setting is required where there is little continental mud or carbonate sediment to dilute the “rain” of dead ...Feb 2, 1998 · Chert, also known as flint, is one of the most abundant rocks in Missouri, and is composed of one of the most common minerals on earth. In fact, in much of Missouri you could say that chert is "common as dirt." Chert is a hard, fine-grained rock made up mostly of the mineral silica (SiO2). Silica itself contains the elements silicon and oxygen ... The type of rock that the fragments were produced from is often used as an adjective when referring to the rock. Some examples: sandstone breccia, limestone breccia, granite breccia, chert breccia, basalt breccia, and others. Often a breccia will contain many types of angular rock fragments. These are known as polymict breccias or polymictic ... Higher organic content can lead to grey or black chert rocks and higher amounts of iron oxides lead to red colour. Types of Chert Rock. There exists a large variety in the types of chert, which depends on the chert minerals, their visibility and physical properties. Let us know about some of the chert rock types and their properties. 1. JasperChert is the name for a widespread type of sedimentary rock that is made of silica (silicon dioxide or SiO 2 ). The most familiar silica mineral is quartz in microscopic or even invisible crystals; that is, microcrystalline or cryptocrystalline quartz. Learn more about how it is made and find out what it is made of. Chert IngredientsChert is widespread, but not widely known by the public as a distinct rock type. Chert has four diagnostic features: the waxy luster, a conchoidal (shell-shaped) fracture of the silica mineral chalcedony that composes it, a hardness of seven on the Mohs scale, and a smooth (non-clastic) sedimentary texture.siliceous rock, any of a group of sedimentary rocks that consist largely or almost entirely of silicon dioxide (SiO 2 ), either as quartz or as amorphous silica and cristobalite; included are rocks that have formed as chemical precipitates and excluded are those of detrital or fragmental origin. The most common siliceous rock is chert, which is ... What is Chert? Chert is a sedimentary rock, mostly composed of silica. It is formed in the sediment precursors of limestone and chalk, mostly produced on the ocean floor. Microscopic organisms in the ocean have skeletons made of silica, which fall to the bottom of the ocean, dissolve, re-crystalize, and then petrify into chert.The problems with chert come in its origin; it’s another one of those rocks whose origin we have a hard time observing directly. The relative importance of nodular chert and bedded chert has changed through geologic time: bedded chert is much more common in the Precambrian, and nodular chert is more common in the Phanerozoic. 1.2 TerminologyFound in the 3.5-billion-year old Apex Chert rock formation in Western Australia, the fossils were initially accepted as being oxygen-producing cyanobacteria, but debates have raged over whether ...Chert (/ ˈ tʃ ɜːr t /) is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO 2). Chert is characteristically of biological origin, but may also occur inorganically as a chemical precipitate or a diagenetic replacement, as in petrified wood .According to National Geographic, the main difference between rocks and stones, or gemstones, are their rarity and crystal formation. Most gemstones have a crystal formation, which makes them rare and valuable after they are cut.Oct 12, 2021 · Chert is a fine-grained sedimentary rock mainly composed of quartz. It can be white, gray, yellow, or brown in color. In Wisconsin, it is prominent in mounds capped by chert in the southwestern part of the state that are roughly 425 to 475 million years old. Varieties of flint, chert, and volcanic glass for flint knapping. Spalls, flakes, and raw rock sold by the pound selected specially for lithic reduction. If you are not sure on where to begin, please visit our Flint Knapping Buyer's Guide for tips on tool selection and stone purchasing. You may also feel free to Contact Us with any questions.Chert. Commonly known as flint, chert is found in many Kansas limestones as nodules or continuous beds. It is a sedimentary rock composed of microscopic crystals of quartz (silica, SiO 2).It is opaque and ranges in color from white to dull gray or brown to black. Chert breaks with a shell-like fracture, and the edges of the broken pieces are sharp.The other concern is that certain cherts undergo an alkali-silica reaction with high-alkali cements. This reaction leads to cracking and expansion of concrete and ultimately to failure of the material. Return to Minerals Database. Chert, also known as flint, is a silica-rich sedimentary rock. Chert is very hard and its conchoidal fractures can ...Download scientific diagram | - Silica rocks under thin section: (A) Chert with chalcedony and mosaic quartz, crossed nicols. The width of the photomicrograph is 1 mm. (B) Chert with mosaic of ...Chert is rock formed from the siliceous ooze on the seabottom that accumulated from the glassy or siliceous skeletons of radiolarians and diatoms. The three basic types of biochemical (biogenic) sedimentary rocks are classified according to their original material: limestone (calcium carbonate), coal (carbon), and chert (silica). …Chert (/ ˈ tʃ ɜːr t /) is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO 2). Chert is characteristically of biological origin, but may also occur inorganically as a chemical precipitate or a diagenetic replacement, as in petrified wood . Sedimentary rock - Clastic, Chemical, Organic: Conglomerates and breccias are sedimentary rocks composed of coarse fragments of preexisting rocks held together either by cement or by a finer-grained clastic matrix. Both contain significant amounts (at least 10 percent) of coarser-than-sand-size clasts. Breccias are consolidated rubble; their clasts …Two major types of iron-rich sedimentary rocks are recognized: (1) iron formation, or banded iron formation (BIF)—regionally extensive, locally thick sequences composed of alternating thin (millimetre to centimetre thick) layers of mainly crystalline-textured iron-rich minerals and chert—and (2) ironstone—noncherty, essentially clastic ...Paleozoic chert gravel is most of the available rock material. There is a significant increase in variety and frequency in the component of igneous rocks as compared to the ancestral Mississippi River Pre-loess Terrace Gravels of the western Loess Bluff Region, particularly the presence of Canadian granite.The rock diversity in New Mexico is quite generous, especially for the trained eye. You can find geodes, obsidian, agate, flint, moonstones, apache tears, staurolite, sandstone, limestone, chert, and other types of igneous, …Chert. Commonly known as flint, chert is found in many Kansas limestones as nodules or continuous beds. It is a sedimentary rock composed of microscopic crystals of quartz (silica, SiO 2 ). It is opaque and ranges in color from white to dull gray or brown to black. Chert breaks with a shell-like ( conchoidal) fracture, and the edges of the ... 10-Aug-2020 ... Chert is a microcrystalline quartz mineral. It consists of many black rock fragments inside the chert called clasts. Chert's color is due to the ...Biological processes are important in the formation of some chemical sedimentary rocks, especially limestone, chert, and coal. For example, limestone is made up almost entirely of fragments of marine [1] organisms that manufacture calcite for their shells and other hard parts, and most chert includes at least some of the silica tests (shells ...Chert is a fine-grained, silica-rich, microcrystalline, cryptocrystalline or microfibrous 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 ... Chert is a quite general term for noncrystalline siliceous rocks, and some subtypes have their own names and stories. In mixed calcareous and siliceous sediments, the carbonate and the silica tend to segregate. Chalk beds, the calcareous equivalent of diatomites, may grow lumpy nodules of chert of the type called flint.Varieties of flint, chert, and volcanic glass for flint knapping. Spalls, flakes, and raw rock sold by the pound selected specially for lithic reduction. If you are not sure on where to begin, please visit our Flint Knapping Buyer's Guide for tips on tool selection and stone purchasing. You may also feel free to Contact Us with any questions. Chert is a microcrystalline or cryptocrystalline sedimentary rock material composed of silicon dioxide (SiO 2).It occurs as nodules and concretionary masses, and less frequently as a layered deposit. Mar 27, 2023 · Beaches, Creeks, Streams, Washes, and Draws. Tiny silica fossils significantly contributed to the formation of chert rocks, especially those at the bottom of the ocean. In such formations, shale is also commonly discovered. Because of this, beaches are also among the best environments to find chert specimens. Nov 1, 2016 · Chert, prized by Native Americans but despised by many farmers, is one of Missouri’s most common rocks. It has all the characteristics which can make a stone both hated and hunted, coveted or cursed. Chert is also a rock of many names and disguises. Few people other than geologists actually call it chert, which is generally applied to the ... Epiclastic and volcaniclastic rocks, chert, limestone, and lava flows of mid- or Early Permian(?) age that are moderately to intensely metamorphosed. Includes part of Hunsaker Creek Formation of Vallier (1977), in the eastern Blue Mountains province, composed mostly of keratophyre flows, keratophyric volcaniclastic rocks and minor spilite ...Nov 28, 2022 · Chert is a broad term for chemically precipitated sedimentary rocks made up of microcrystalline silica. Most charts are nearly pure silica with up to 5% other minerals like calcite, dolomite, clay minerals, hematite, and organic matter. Some cherts may have up to 99% silica, while others have 65% silica content. Chert is a microcrystalline rock consisting almost exclusively of silica. Chert may occur as stratiform units, with often-spectacular laminar alteration of colors (red, white, black, green), in dykes crosscutting the stratigraphy, or, in modern limestones, as nodules. Stratiform cherts in Archean greenstone belts represent the earliest ... Quartz is the most abundant mineral. It is an essential component of granitic igneous rocks, of sedimentary rocks such as sandstone and chert and of metamorphic rocks such as quartzites. It is a common hydrothermal mineral and forms in amygdules in volcanic rock, sometimes in the form of Lake Superior agate. It forms as a groundwater precipitate, and can form sparkling crystals lining cavities ... Rocks are important because geologists use evidence from them to learn about what the Earth was like in the past. They allow scientists to build a historical record of the planet to learn what events occurred before people lived.The type of rock that the fragments were produced from is often used as an adjective when referring to the rock. Some examples: sandstone breccia, limestone breccia, granite breccia, chert breccia, basalt breccia, and others. Often a breccia will contain many types of angular rock fragments. These are known as polymict breccias or polymictic ... Feb 2, 1998 · Chert, also known as flint, is one of the most abundant rocks in Missouri, and is composed of one of the most common minerals on earth. In fact, in much of Missouri you could say that chert is "common as dirt." Chert is a hard, fine-grained rock made up mostly of the mineral silica (SiO2). Silica itself contains the elements silicon and oxygen ... Flint, chert, and jasper are names commonly used by geologists and by the general public for opaque specimens of microcrystalline quartz. The same hand specimen might be called "chert" by one person, "flint" by another, and "jasper" by a third. The name used can be influenced by the educational background of the person, the physical properties ... Chert, prized by Native Americans but despised by many farmers, is one of Missouri’s most common rocks. It has all the characteristics which can make a stone both hated and hunted, coveted or cursed. Chert is also a rock of many names and disguises. Few people other than geologists actually call it chert, which is generally applied to the ...Chert. Chert is a widespread type of rock, and its variety and hardness made it a popular stone for polishing into cabochons and other shapes used in jewelry. It is a common ingredient of gravel in streams in the form of Jasper pebbles. Colors range from pink, brown, white, yellow, black, and gray. Chert is resistant to erosion because of its ...The two primary differences between chert and novaculite are: 1) chert is composed mainly of chalcedony while novaculite is composed mainly of microcrystalline quartz grains; and, 2) chert is a sedimentary rock, while novaculite is a chert that has experienced a higher level of diagenetic alteration and low-grade metamorphism.Sedimentary Rocks. Sedimentary rocks (layered rocks) are made by the deposition of particles carried in air or water and by the precipitation of chemicals dissolved in water. These particles and chemicals come from the weathering (breaking apart in place) and erosion (carrying away and breaking apart while moving) of rocks on the Earth’s surface.Nov 28, 2020 · Chert is a sedimentary rock that is typically found in nodules in surrounding limestone. Chert rock is mainly comprised of microcrystalline crystals of quartz. There are some formations of chert rock that can be excluded of biological remains, but typically they are present in this rock. The remains of open sea life find their way to the bottom ... Among the siliceous sedimentary rocks the cherts are dominant, being described as siliceous hard-dense rocks consisting mainly of micro to cryptocrystalline quartz and low impurities, ranging in ...The Acid Test on Rocks. LIMESTONE, DOLOSTONE, AND MARBLE. Some rocks contain carbonate minerals, and the acid test can be used to help identify them. Limestone is composed almost entirely of calcite and will produce a vigorous fizz with a drop of hydrochloric acid. Dolostone is a rock composed of almost entirely of dolomite. It will produce a ... Chert is a sedimentary rock, mostly composed of silica. It is formed in the sediment precursors of limestone and chalk, mostly produced on the ocean floor. Microscopic organisms in the ocean have skeletons made of silica, which fall to the bottom of the ocean, dissolve, re-crystalize, and then petrify into chert.The 'Rhynie chert' is located near the village of Rhynie in north east Scotland, a village approximately 50km north west of Aberdeen (see insets below). The rock itself does not naturally outcrop at the surface. Most fossiliferous …What is Chert? Chert is a sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO 2). It occurs as nodules, concretionary masses, and as layered deposits. Chert breaks with a conchoidal fracture, often producing very sharp edges.Sometimes referred to as flint, Chert is a sedimentary rock rich in silica. This specimen is perfect for teaching geology students about the many forms of ...Quartz is the most abundant mineral. It is an essential component of granitic igneous rocks, of sedimentary rocks such as sandstone and chert and of metamorphic rocks such as quartzites. It is a common hydrothermal mineral and forms in amygdules in volcanic rock, sometimes in the form of Lake Superior agate. It forms as a groundwater precipitate, and can form sparkling crystals lining cavities ...Feb 13, 2023 · Chert breccia. Rock Type: Sedimentary – A poorly sorted and immature detrital (clastic) sedimentary rock made up of angular rock fragments that are gravel sized or larger (2mm or more). Click on image to see enlarged photo. Chert. Commonly known as flint, chert is found in many Kansas limestones as nodules or continuous beds. It is a sedimentary rock composed of microscopic crystals of quartz (silica, SiO 2).It is opaque and ranges in color from white to dull gray or brown to black. Chert breaks with a shell-like fracture, and the edges of the broken pieces are sharp.Chert: Chert is a rock composed of very small microscopic quartz crystals. It can be distinguished from dolomite because it is much harder than dolomite. Chert cannot be easily scratched by a nail and will easily scratch a glass plate. It also will not react with dilute acid as dolomite powder does. Potassium or Plagioclase Feldspar:Chert is a hard and compact sedimentary rock, consisting dominantly of very small quartz crystals. It is a common rock type which occurs mostly in carbonate rocks either in nodular form or in layers (bedded chert). Flint on the coast at Stevns Klint in Denmark. Oct 9, 2019 · Chert is a sedimentary rock composed mostly of the mineral chalcedony—cryptocrystalline silica in crystals of submicroscopic size. This type of sedimentary rock can form in parts of the deep sea where the tiny shells of siliceous organisms are concentrated, or elsewhere where underground fluids replace sediments with silica. A rock garden is a unique way to decorate your yard and create a positive impression with visitors. Certain landscapes are more suitable for rock gardens than others. To avoid overwhelming yourself with a complicated scheme for the whole ba...Chert is a sedimentary rock comprised of microcrystalline Quartz which makes it fairly hard, 7 on the Mohs Hardness Scale. It exhibits conchoidal fracturing and …RHYOLITE — A fine-grained igneous rock shaped into a convex gem form known as a cabochon. The group of four banded reddish brown pebbles immediately beneath are also rhyolite. 28. CHERT—with small orbs of red jasper. 29. CHERT—just chert, but most unusual and pleasing gem specimens. 30. DATOLITE — often very colorful, and though not as Chert is a sedimentary rock that is typically found in nodules in surrounding limestone. Chert rock is mainly comprised of microcrystalline crystals of quartz. There are some formations of chert rock that can be excluded of biological remains, but typically they are present in this rock. The remains of open sea life find their way to the bottom ...Quartzite is a tough stone composed mostly of quartz. It may be derived from sandstone or from chert by regional metamorphism. This metamorphic rock forms in two different ways. In the first way, sandstone or chert recrystallizes resulting in a metamorphic rock under the pressures and temperatures of deep burial.Oct 12, 2021 · Chert is a fine-grained sedimentary rock mainly composed of quartz. It can be white, gray, yellow, or brown in color. In Wisconsin, it is prominent in mounds capped by chert in the southwestern part of the state that are roughly 425 to 475 million years old. Looking for flint rock online in India? Shop for the best flint rock from our collection of exclusive, customized & handmade products.26-Oct-2002 ... "Rock of the Month # 16, posted October 2002" Chert is a very fine-grained variety of silica, composed largely of cryptocrystalline quartz, ...To identify your rock, first take note of its physical properties like color, luster, banding, layering, and grain size. Next, test for hardness and weight by running simple tests. Finally, compare the properties of your rock to those of known rock types while looking for other identifying characteristics. Identifying and classifying rocks can ...The iron formation we see today consists of thinly layered red, white, and black minerals. The red layers are jasper; the white, chert (mostly quartz); and the black are iron-bearing minerals, mostly magnetite (magnetic) and hematite (nonmagnetic). An example of this type of rock can be seen at Soudan Underground Mine State Park.Flint is a high-quality variety of chert, a biochemical sedimentary rock made of cryptocrystalline quartz. It is very hard, with characteristic conchoidal fracturing that makes it exceptionally useful for the creation of tools like arrowheads. Flint comes in many colors but is usually dark gray or black.What is Chert? Chert as a geologic formation is a sedimentary rock that can serve as a reservoir for oil and gas. For example, in West Virginia, a large pocket of natural gas occurs within such as the rock formation, known as the Huntersville Chert. Chert can take on various colors. Gray is common, as is white and pink.Chert can be a chemical sedimentary rock, often forming as beds within limestone (Figure 5.14), or as irregular lenses or blobs (nodules). It can also be biochemical. Some tiny marine organisms (e.g., diatoms and radiolaria) make their tests from silica.Chemical Composition and Physical Characteristics of Granite. Granite is an Igneous rock composed of quartz, biotite, muscovite, feldspars, and occasionally several others, including hornblende, zircon, augite, and magnetite. Typically, granite is between 70 and 77 % silica, 11 to 13% alumina, 3 to 5 % potassium oxide and a smaller percentage ...Flint, chert, and jasper are names commonly used by geologists and by the general public for opaque specimens of microcrystalline quartz. The same hand specimen might be called "chert" by one person, "flint" by another, and "jasper" by a third. The name used can be influenced by the educational background of the person, the physical properties ...
Tendency to chemical cement. Ash: unconsolidated fragments under. 4 mm. Tuff: consolidated ash. Volcanic Breccia: angular fragments over 4 mm. Agglomerate: large proportion (>25%) of bombs. These rocks are classified on the proportions of vitric, crystal (mineral), or lithic material they contain, for example, "vitric lithic ash," or "crystal .... Kansas demographics
5.1.4 Chert. Chert is by far the most abundant lithic fragment preserved in the Tantalus formation, making up 77% of the framework of the conglomerate and 56% of the sandstone. This is in marked contrast with the underlying Tanglefoot formation, in which only 16% of the framework grains in conglomerates and 5.5% in sandstones consist of chert.Flint Knapping was a critical skill for early humans across the globe. The ability to remove flakes of rock to create a sharp edge shaped our evolution. Flint knapping in finer detail allowed for the specific shaping of tools and edge work for specific tasks. Knapping was essential for create projectile points, knives, scrapers, gravers, drills ...Chert can be a chemical sedimentary rock, often forming as beds within limestone (Figure 5.14), or as irregular lenses or blobs (nodules). It can also be biochemical. Some tiny marine organisms (e.g., diatoms and radiolaria) make their tests from silica.Quartz and chert (another silica rock) are very durable, and persist as solid particles in the surface environment for a very long time, so they can come from ...Flint formed in silt is notorious for having sand pockets and coarse areas referred to as "concrete". Course opaque silica with impurities is called chert. Chert, flint and jasper are opaque forms of ultrafine-grained quartz. Jasper is distinctively red or multicoloured. Flint is a hard variety of chert, often found as nodules in limestone.Sedimentary rock - Iron-Rich, Clastic, Chemical: Almost all sedimentary rocks are iron-bearing in the sense that mudrocks, sandstones, and carbonates typically have an iron content of several percent. Nevertheless, sedimentary rocks in which the proportion of iron exceeds 15 percent are separately categorized as iron-rich. Two major types of iron-rich …Similar reactions have been proposed to explain the presence of organic molecules in Martian meteorites and in some igneous rocks on Earth. The carbon in black cherts from the Pilbara outback may ...Autism Rocks and Rolls Raises awareness about autism. It's a podcast and business that proves just how powerful one person can be. About 1 in 54 children have been identified as having Autism Spectrum Disorder. And many of these kids go ont...Autism Rocks and Rolls Raises awareness about autism. It's a podcast and business that proves just how powerful one person can be. About 1 in 54 children have been identified as having Autism Spectrum Disorder. And many of these kids go ont...Flint, chert, and jasper are names commonly used by geologists and by the general public for opaque specimens of microcrystalline quartz. The same hand specimen might be called "chert" by one person, "flint" by another, and "jasper" by a third. The name used can be influenced by the educational background of the person, the physical properties ...Chert is a sedimentary rock comprised of microcrystalline Quartz which makes it fairly hard, 7 on the Mohs Hardness Scale. It exhibits conchoidal fracturing and you'll typically see colors ranging from brown, gray, green, or red.Flint, chert, and jasper are names commonly used by geologists and by the general public for opaque specimens of microcrystalline quartz. The same hand specimen might be called "chert" by one person, "flint" by another, and "jasper" by a third. The name used can be influenced by the educational background of the person, the physical properties ...The formation is composed largely of dark limestone and dolomite, and contains black chalcedonic chert ... rocks, and along with fossils found in the Gunflint ....