Chert grain size - “Akademikerbreen cherts occur as ellipsoidal to irregular nodules, individually silicified grains in oolites and flake conglomerates, and individually silicified laminae of a probable …

 
Study with Quizlet and memorize flashcards containing terms like Which statement is TRUE? Conglomerates consist of a single grain size. Pieces of broken rock produced by physical weathering are collectively called clasts or detritus. A well sorted clastic rock is made up of different-sized particles. An immature clastic rock has well-sorted, resistant …. Who playing basketball

The fine grain size, the horizontal lamination, and the straight boundaries indicate a low-energy environment. It can thus be deduced that the micrites accumulated in a quiet deep-sea environment. Also, the mudstones (A-3) between the deep-sea micrites suggest a deep-sea environment. Chert Grain Size (chemical) Sorting Roundness Layered? Fossils? Acid Reaction? Conglomerate Grain Size (clastic) Sorting Roundness Layered? Fossils? Acid. Show transcribed image text. Expert Answer. Who are the experts? Experts are tested by Chegg as specialists in their subject area. We reviewed their content and use your feedback to …Grain size charts. Use these grain size cards in your observations of sedimentary rocks. You can use them for hand specimens at home or in the classroom, or on rock outcrops outdoors. If you are a beginner geologist, or using these in a KS2 classroom, we would recommend starting with the ‘bite size’ card. We recommend printing on card or ...23 ene 2019 ... Quartz and silica occur in many varieties—true quartz in the form of megaquartz, chert ... Grain size can make provenance determination more ...Clastic sedimentary rocks are subdivided on the basis of grain size. Secondary characteristics used to further distinguish clastic rocks are sorting, grain shape, and grain composition. Grain size: Clastic sediments are distinguished on the basis of average grain size. gravel-size particles are larger than 2 mm diameter Science. Earth Sciences. Earth Sciences questions and answers. DQuestion 1 3 pts Match the physical properties to the appropriate rock name Breccia IChoose ] I Choose ] GRAIN SIZE: sand to pebble sized; SORTING: poorly sorted; ROUNDNESS: rounded to subrounded; LAYERED: no; FOSSILS: no; ACID REACTION: no GRAIN SIZE: sand to pebble sized: SORTING ...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 ... 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 ...Chert: This specimen of gray chert is about two inches (five centimeters) across. It breaks with a smooth conchoidal fracture. Edges of the piece have sharp edges as a result of the conchoidal fracture. ADVERTISEMENT What is Chert? Get ratings and reviews for the top 10 gutter companies in Grain Valley, MO. Helping you find the best gutter companies for the job. Expert Advice On Improving Your Home All Projects Featured Content Media Find a Pro About Please enter a va...Grain size - cryptocrystalline, cannot be seen except under very high magnification. Hardness - hard. Colour - all colours, dependent on impurities present when precipitated. Clasts - none. Other features - smooth to …B-Same thin section of A, another sector, highly compacted carbonate grains in contact with chert nodule. C-Schematic models of the diagenetic evolution: 1-Formation of early dolomite followed by ...Grain size - cryptocrystalline, cannot be seen except under very high magnification. Hardness - hard. Colour - all colours, dependent on impurities present when precipitated. Clasts - none. Other features - smooth to touch, glassy, exhibits conchoidal fracture. Uses - mainly decorative; ancient cultures used chert for cutting tools, arrow heads ...lithic wacke. Dominated by sand (1/16 to 2 mm), greater than 10% rock fragments, greater than 15% silt and clay, range of roundness and sorting possible. Mudrock. mudstone. Greater than 75% silt (1/256 to 1/16 mm) and clay (<1/256 mm), not bedded, well-sorted, grains too fine to judge roundness using hand lens. shale. e. Wentworth grain size chart from United States Geological Survey Open-File Report 2006-1195: Note size typos; 33.1mm is 38.1 & .545mm is .594. Beach cobbles at Nash Point, South Wales. Grain size (or particle size) is the diameter of individual grains of sediment, or the lithified particles in clastic rocks. 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.sedimentary rock. 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 ...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 …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 …A thin section of a clast (sand grain), derived from a basalt scoria. Vesicles (air bubbles) can be seen throughout the clast. Plane light above, cross-polarized light below.Scale box is 0.25 mm. Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus, chunks, and smaller grains of rock …sands such as the Eutaw, which contains chert grains. Sand from Locality No ... Larger average grain size and uniformity of grain size in indi- vidual areas ...Physical properties of rocks are used to identify the type of rocks and to discover more about them. There are various physical properties of Flint like Hardness, Grain Size, Fracture, Streak, Porosity, Luster, Strength etc which defines it. The physical properties of Flint rock are vital in determining its Flint Texture and Flint Uses.Gray chert in tan limestone in Chase County. Commonly called flint, chert is a fine-grained, noncrystalline sedimentary rock made up of silicon dioxide (SiO 2 ). (The mineral quartz has the same chemical formula.) Chert …Grain size - cryptocrystalline, cannot be seen except under very high magnification. Hardness - hard. Colour - all colours, dependent on impurities present when precipitated. Clasts - none. Other features - smooth to touch, glassy, exhibits conchoidal fracture. Uses - mainly decorative; ancient cultures used chert for cutting tools, arrow heads ...CHERT. Chert is a chemical precipitate formed by groundwater. Chert can also form by biochemical accumulation of silica-rich fossils in deep marine environments; however, distinction requires microscopic examination. Sediment type: chemical/biogenic; Composition: quartz; Grain Size: microscopic Clastic sedimentary rocks may have particles ranging in size from microscopic clay to huge boulders. Their names are based on their clast or grain size. The smallest grains are called clay, then silt, then sand. Grains larger than 2 millimeters are called pebbles. ... Chert is an example for this type of rock, and this is one of the ways ...Chert, a chemically precipitated monomineralic sedimentary rock composed of microcrystalline and cryptocrystalline quartz, with subordinate mega quartz and minor amounts of impurities (Folk, 1980 ), exhibits wide variation in occurrence.Sedimentary rock - Silica, Clastic, Chemical: Those siliceous rocks composed of an exceptionally high amount of crystalline siliceous material, mainly the mineral quartz (especially microcrystalline quartz and fibrous chalcedony) and amorphous opal, are most commonly known as chert. A wide variety of rock names are applied to cherty rocks reflecting their colour (flint is dark chert; jasper is ...For example, the portion of the key below requires a number of observations: grain size, conchoidal fracture, hard enough to scratch fingernail, etc. The degree ...1 day ago · Study with Quizlet and memorize flashcards containing terms like Which of the following statements is true? Choose one: A. Conglomerates consist of a single grain size. B. An immature clastic rock has well-sorted, resistant grains. C. A well-sorted clastic rock is made up of different-sized particles. D. Pieces of broken rock produced by physical weathering are collectively called clasts or ... Conglomerate ( / kənˈɡlɒmərɪt /) is a clastic sedimentary rock that is composed of a substantial fraction of rounded to subangular gravel -size clasts. A conglomerate typically contains a matrix of finer-grained sediments, such as sand, silt, or clay, which fills the interstices between the clasts. The clasts and matrix are typically ...Conglomerate is a clastic sedimentary rock made up of rounded clasts that are greater than two millimeters in diameter. The spaces between the clasts are generally filled with sand- and clay-size particles. The rock is bound together by a cement that is usually composed of calcite or quartz.Chert nodule. Nodules of chert are rounded to elongated silica-rich lumps that occur within sequences of limestones (commonly chalk and calcilutites). They originate from the diagenesis of an original silica-rich carbonatic ooze, containing remains of organisms like radiolarians or diatoms, which produce shells made of silica.Animal microchipping is a simple and effective way to keep your pet safe and secure. A microchip is a small device, about the size of a grain of rice, that is implanted under your pet’s skin.In sandstones with a high content of detrital quartz and chert, grain size may also affect porosity. Permeability can be expressed by the same parameters as porosity. Most important, the independent variables that correlate with porosity and permeability can be often estimated prior to drilling from facies models and seismic data. Accurate ...coarse sand (1 to 2 mm). (c) The term clay can refer either to a range of grain size (< 1/256 mm) or to a family of sheet silicate minerals known as clay minerals. Name of particle . Range limits of diameter (mm) Names ... Chert . Halite . Three perfect cleavages at 90°, tastes salty . Rock Salt . Gypsum . Softer than fingernail, cleavages not ...With the ever-changing dynamics of global agriculture, understanding the factors that influence grain market prices is crucial for farmers, traders, and consumers alike. The supply and demand dynamics play a significant role in determining ...One pound of uncooked long grain rice contains more than 29,000 grains. In the U.S., rice is sold in bags of 2, 5, 10 and 50 pounds. Rice has more than 40,000 species, though only a few varieties are marketed for sale.The size of the grains selected for sample preparation depends on the purpose of the experimental investigation. In this research, to study the effect of grain size on sandstone properties, a wide range of grain size was used. The median grain size, D 50, (the mesh size where 50% of the grain pass through) was selected to be between …determined by the grain density-bulk density relation, was 25.0 percent where the bulk volume was obtained by micrometer measure­ ment, but the total porosity was 23.6 percent where the bulk volume was obtained by mercury displacement. These results indicate that mercury displacement determinations of bulk volume tend towardSee Answer. Question: Part 3. Unknown Samples Here you will use your sedimentary rock identification key ["Sedimentary Rocks ID Charts" PDF on Blackboard) and the practice you had in Parts 1 and 2 to identify some unknown rock samples. To make things clearer, the samples have been grouped into unifying themes. Fill out the table for each sample ...basis of their texture, grain size, and mineralogic composition. Characteristics of sedimentary rocks are described in Pellant p. 38-41and 44-45; Marshak, p. 176-186. Texture: ... Chert is a hard, aphanitic, non-clastic rock …Salts with different grain sizes, grain shapes, additives and origins can have very different tastes. Coarse salts shown in the photo are intended for cooking; however, they can be ground to a smaller particle size for table use or placed in a shaker with a built-in grinder that allows diners to grind the salt ... Chert, and Jasper ...If water is the transport mechanism of sediment, the grain size of sedimentary deposits most closely indicates the _____. a. geographic extent of the weathering source rock at outcrop b. average velocity of the water from the time of erosion until deposition c. velocity of the water at the moment the sediment settled to the bottom d. climate conditions at the time of depositionGrain size: no grain size Components: biochemical/organic Minerals: calcite, with some shells and skeletal fragments Transportation: water. Siltstone. Grain size: < 1/16 mm ... Chert. Grain size: no grain size Components: chemical Minerals: silica (quartz) Transportation: wind. Sandstone. Grain size: 1/16 - 2 mmYou might think the only differences between whole wheat and white bread are superficial things, like texture and taste. But it’s also true that whole wheat bread gets touted as the healthier option.Apr 23, 2023 · Grain size: Cryptocrystalline, cannot be seen except under very high magnification. Hardness: Hard Colour: All colours, dependent on impurities present when precipitated. Clasts: None Other features: Smooth to touch, glassy, exhibits conchoidal fracture. Occurrence of Chert Sedimentary Rocks Figure C: A visual reference for descriptions of sorting (top) and roundness (bottom) of sediments and …1 day ago · Study with Quizlet and memorize flashcards containing terms like Which of the following statements is true? Choose one: A. Conglomerates consist of a single grain size. B. An immature clastic rock has well-sorted, resistant grains. C. A well-sorted clastic rock is made up of different-sized particles. D. Pieces of broken rock produced by physical weathering are collectively called clasts or ... Grain size - cryptocrystalline, cannot be seen except under very high magnification. Hardness - hard. Colour - all colours, dependent on impurities present when precipitated. Clasts - none. Other features - smooth to touch, glassy, exhibits conchoidal fracture. Uses - mainly decorative; ancient cultures used chert for cutting tools, arrow heads ... Breccia forms where broken, angular fragments of rock or mineral debris accumulate. One of the most common locations for breccia formation is at the base of an outcrop where mechanical weathering debris accumulates. Another is in stream deposits a short distance from the outcrop or on an alluvial fan. Some breccias form from debris flow deposits.Matrix material is mostly chert, some hav- ing a grain size of 1-2 μm; in other specimens, grain size is 5-10 μm, and rare grains are as large as 20 μm. are.Grain size is the primary parameter in sedimentary geology to divide clastic rocks and sediments in different classes for classification purposes. This subdivision is based on the Udden-Wentworth scale, which differentiates four major classes of sediments (and corresponding sedimentary rocks) that are further divided in sub-classes:Study with Quizlet and memorize flashcards containing terms like Texture: Clastic (course) Composition: Chert Grain size: sand/silt-gravel (mostly gravel) sorting: poorly sorted roundness: angular Fossils: N/A Identifying markers: scratches glass, large angular chunks, Texture: Clastic (course) Composition: Quartz (Iron oxide?) Grain size: sand-pebble (mostly pebble) sorting: poorly sorted ... 9 ago 2022 ... Chert is a type of sedimentary rock. Sedimentary rocks are formed when wind or other erosion factor transports and accumulates sediments and ...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.Chert from the Portland Roach can be recognised easily because of the large molluscs and particularly the gastropod Aptyxiella portlandica . Striking constituent are the discoidal pebbles of quartzite, red, purple ("liver-coloured" or white) such as occur in the Triassic pebble beds at Budleigh Salterton in Devon. ... Note the coarse grain size ...Gypsum deposits can vary in terms of purity, crystal size, and mineral associations. The quality and characteristics of gypsum in a particular location depend on the geological history and environmental conditions of that region. Gypsum is a valuable mineral resource used in construction, agriculture, industry, and various other applications.Grain size is the primary parameter in sedimentary geology to divide clastic rocks and sediments in different classes for classification purposes. This subdivision is based on …Get ratings and reviews for the top 10 gutter companies in Grain Valley, MO. Helping you find the best gutter companies for the job. Expert Advice On Improving Your Home All Projects Featured Content Media Find a Pro About Please enter a va...Granular microquartz is the component of chert consisting of roughly equidimensional quartz grains, ranging in size from a fraction of a micron to 20 microns, but most typically 8 to 10 microns. Chalcedony is a microfibrous variety of quartz, consisting of radiating bundles of very thin crystals about 100 microns long.These properties make it useful as a filter media, an absorbent, and as a lightweight filler for rubber, paint, and plastics. When diatomite is crushed into a powder, it is usually called "diatomaceous earth," or D.E. Diatoms are microscopic, single-celled algae that live in marine or fresh water. They produce hard parts made of silicon dioxide.Salts with different grain sizes, grain shapes, additives and origins can have very different tastes. Coarse salts shown in the photo are intended for cooking; however, they can be ground to a smaller particle size for table use or placed in a shaker with a built-in grinder that allows diners to grind the salt ... Chert, and Jasper ...Physical properties of rocks are used to identify the type of rocks and to discover more about them. There are various physical properties of Flint like Hardness, Grain Size, Fracture, Streak, Porosity, Luster, Strength etc which defines it. The physical properties of Flint rock are vital in determining its Flint Texture and Flint Uses. An average grain of sand weighs approximately 50 micrograms, and a grain of very fine sand can weigh as little as 350 nanograms. The size of grains of sand vary because they are not uniform.Chert is a biochemical sedimentary rock made from microcrystalline quartz. It is very hard – registering a 7 on the Mohs hardness scale, and displays conchoidal fracturing. Chert can almost any color, but is usually gray, brown, red, or green. It has many subvarieties including flint, jasper, agate, and onyx.Chert Grain Size (chemical) Sorting Roundness Layered? Fossils? Acid Reaction? Conglomerate Grain Size (clastic) Sorting Roundness Layered? Fossils? Acid. Show transcribed image text. Expert Answer. Who are the experts? Experts are tested by Chegg as specialists in their subject area. We reviewed their content and use your feedback to …Chert Grain Size (chemical) Sorting Roundness Layered? Fossils? Acid Reaction? Conglomerate Grain Size (clastic) Sorting Roundness Layered? Fossils? Acid. Show transcribed image text. Expert Answer. Who are the experts? Experts are tested by Chegg as specialists in their subject area. We reviewed their content and use your feedback to …Chert: This specimen of gray chert is about two inches (five centimeters) across. It breaks with a smooth conchoidal fracture. Edges of the piece have sharp edges as a result of the conchoidal fracture. ADVERTISEMENT What is Chert?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 …Chert is a biochemical sedimentary rock made from microcrystalline quartz. It is very hard – registering a 7 on the Mohs hardness scale, and displays conchoidal fracturing. Chert can almost any color, but is usually gray, brown, red, or green. It has many subvarieties including flint, jasper, agate, and onyx.A number of classification schemes have been proposed to further subdivide conglomerates and breccias. One scheme is purely descriptive, partitioning these coarse clastic sedimentary rocks on the basis of grain size (e.g., boulder breccia versus cobble conglomerate) or composition or both (chert pebble breccia versus limestone cobble conglomerate).... particle-size as well. The rock fragments are dominantly angular chert pebbles or cobbles. In some places the fragments are sub-rounded. Some limestone ...There are various physical properties of Chert like Hardness, Grain Size, Fracture, Streak, Porosity, Luster, Strength etc which defines it. The physical properties of Chert rock are vital in determining its Chert Texture and Chert Uses. Hardness and Strength of Chert. The physical properties of Chert depend on its formation.The texture of a detrital sedimentary rock is determined by its grain size, grain sorting, and grain roundness. ... The most common rocks formed by this process are limestone and chert.claystone - 1. siltstone - 2. sandstone - 3. conglomerate - 4. Put the sediments shown below in order according to how well sorted they are. List them from well sorted to poorly sorted. PHOTO 1. B, C, A. The rock in the image below contains clasts that are larger than sand and are partially rounded.Grain size - cryptocrystalline, cannot be seen except under very high magnification. Hardness - hard. Colour - all colours, dependent on impurities present when precipitated. Clasts - none. Other features - smooth to touch, glassy, exhibits conchoidal fracture. Uses - mainly decorative; ancient cultures used chert for cutting tools, arrow heads ...Grain silos are an essential part of on-farm storage for many farmers. These structures are used to store grains such as corn, wheat, and soybeans until they are ready to be sold or processed. In this article, we’ll take a closer look at th...Grain size is the primary parameter in sedimentary geology to divide clastic rocks and sediments in different classes for classification purposes. This subdivision is based on …Size Grades (mm): 2-4 granules; 4-64 pebbles; 64-256 cobbles; >256 boulders: Composition of Major ...... grains. Quartz grains freshly released from a weathered rock can be quite ... Chert is great for making arrowheads and scrapers because the size of the ...Sep 8, 2023 · Grain Size. Most chert is microcrystalline, meaning the individual quartz crystals are under 10-50 microns in size and indistinguishable to the naked eye. Some varieties like flint are cryptocrystalline, with even smaller grains under 5 microns. Quartz. Quartz makes up over 90% of chert in most cases. 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 ...An average grain of sand weighs approximately 50 micrograms, and a grain of very fine sand can weigh as little as 350 nanograms. The size of grains of sand vary because they are not uniform.Sedimentary rock - Silica, Clastic, Chemical: Those siliceous rocks composed of an exceptionally high amount of crystalline siliceous material, mainly the mineral quartz (especially microcrystalline quartz and fibrous chalcedony) and amorphous opal, are most commonly known as chert. A wide variety of rock names are applied to cherty rocks reflecting their colour (flint is dark chert; jasper is ... Grain size is the average diameter of sediment fragments in sediment or rock. Grain sizes are delineated using a logbase-2 scale [9; 10]. For example, the grain sizes in the pebble class are 2.52, 1.26, 0.63, 0.32, …Types of Chemical Sedimentary Rocks - Rock Salt (Halite), Gypsum, Chert (silica). Mineral Deposits include iron and phosphorus deposits) Biogenic Sediment - a sediment composed mainly of fossil remains. Diatomite - composed of the remains of algae (diatoms). Radiolarian chert - composed of the remains of floating protozoa called radiolarians.

Class: Conglomerate may be divided into large lessons: Texture: Clastic (coarse-grained).. Grain size: > 2mm; Clasts easily visible to the naked eye, should be identifiable. Hardness: Soft to hard, dependent on clast composition and strength of cement. Colour: variable, dependent on clast and matrix composition. Clasts: variable, but …. Concur mobile app training

chert grain size

Oolite or oölite (from Ancient Greek ᾠόν (ōión) 'egg stone') [1] is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. [2] Strictly, oolites consist of ooids of diameter 0.25–2 millimetres; rocks composed of ooids larger than 2 mm are called pisolites. The term oolith can refer to oolite or individual ...Texture: Grain Size Grain size is used to describe the size of the individual mineral grains, rock fragments, or organic material that are cemented together to form a clastic or chemical sedimentary rock Grain Size Categories Grain Size Divisions very coarse-grained > 16 mm coarse grained > 2 mm < 16 mm medium grained > 0.25 mm < 2 mmChert Attributes and Signs. Chert is as hard as crystalline quartz with a hardness rating of seven in the Mohs scale, maybe a bit softer, 6.5, if it still has some hydrated silica in it. Beyond simply being hard, chert is a tough rock. It stands above the landscape in outcrops that resist erosion.claystone - 1. siltstone - 2. sandstone - 3. conglomerate - 4. Put the sediments shown below in order according to how well sorted they are. List them from well sorted to poorly sorted. PHOTO 1. B, C, A. The rock in the image below contains clasts that are larger than sand and are partially rounded.Chert is as hard as crystalline quartz with a hardnessrating of seven in the Mohs scale — maybe a bit softer, 6.5, if it still hassome hydrated silica in it. Beyond simply being hard, chert is a tough rock. Itstands above the landscape in outcrops that resist erosion. Oil drillers dreadit because it’s so hard to penetrate. It … See moreDetrital sedimentary rocks are mainly classified by the size of their grain. The largest grain is a boulder, followed by a cobble, a pebble, sand, silt and finally the finest grain, which is clay.Grain Size: Coarse grains are visible to the naked eye, and the minerals can usually be identified without using a magnifier. Fine grains are smaller and usually cannot be identified without using a magnifier.; …Physical properties of rocks are used to identify the type of rocks and to discover more about them. There are various physical properties of Flint like Hardness, Grain Size, Fracture, Streak, Porosity, Luster, Strength etc which defines it. The physical properties of Flint rock are vital in determining its Flint Texture and Flint Uses.Texture: Grain Size Grain size is used to describe the size of the individual mineral grains, rock fragments, or organic material that are cemented together to form a clastic or chemical sedimentary rock Grain Size Categories Grain Size Divisions very coarse-grained > 16 mm coarse grained > 2 mm < 16 mm medium grained > 0.25 mm < 2 mmlithic wacke. Dominated by sand (1/16 to 2 mm), greater than 10% rock fragments, greater than 15% silt and clay, range of roundness and sorting possible. Mudrock. mudstone. Greater than 75% silt (1/256 to 1/16 mm) and clay (<1/256 mm), not bedded, well-sorted, grains too fine to judge roundness using hand lens. shale. In the chert of Xionger Group, there were clear banded (or lamellar) structures which were contributed by the diversities of the grain size and mineral composition. The different bands (or lamellars) had alternative appearance repeatedly, and denoted the diversities and periodic changes in the substance supply during the precipitation.Chert nodule. Nodules of chert are rounded to elongated silica-rich lumps that occur within sequences of limestones (commonly chalk and calcilutites). They originate from the diagenesis of an original silica-rich carbonatic ooze, containing remains of organisms like radiolarians or diatoms, which produce shells made of silica. .

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