The State of England’s Chalk Streams report provides a health check for our chalk streams and reveals that over three quarters of them are not in good health. From 2014 to 2017 we led the exciting WaterLIFE project with The Rivers Trust and Westcountry Rivers Trust to improve the health of our rivers. We produced a wealth of guidance, reports ...Chalk. Chalk is the name of a limestone that forms from an accumulation of calcareous shell remains of microscopic marine organisms such as foraminifera. It can also form from the calcareous remains of some marine algae. Chalk is a friable limestone with a very fine texture, and it is easily crushed or crumbled. Limestone is a type of rock that is made up of bits of animal shells. Over millions of years these shells collected on the ocean floor. As layers of shells and mud built up, the lower layers slowly hardened into limestone.chalk: [noun] a soft white, gray, or buff limestone composed chiefly of the shells of foraminifers. a prepared form of chalk or a material resembling chalk especially when used (as for writing on blackboards) as a crayon.Chalk is a sedimentary rock primarily composed of calcium carbonate (calcite). It is formed from the accumulation of microscopic marine organisms' remains, especially coccolithophores. Chalk is known for its distinctive white color, fine-grained texture, and softness. It is commonly associated with marine environments.Many limestone layers also contain fossils of such animals as corals, brachiopods, clams, bryozoans, crinoids, and one-celled fusulinids that were preserved whole or nearly whole. Different types of material form different types limestone. Chalk, for example, is a type of limestone made up mainly of the remains of microorganisms and algae. Pure ... Calcium carbonate occurs naturally as chalk, limestone and marble. The photo shows the reaction with marble chips. You get immediate fizzing with a colourless gas given off - that's carbon dioxide. The marble reacts to give a colourless solution of calcium chloride. CaCO 3 (s) + 2HCl(aq) CaCl 2 (aq) + CO 2 (g) + H 2 O(l)Get ratings and reviews for the top 11 gutter companies in Limestone, IL. 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 valid...There are numerous limestone rock types that differ in shades, colors, and forms because of the different conditions that produce the rock. Here are some examples. Chalk limestone forms from calcareous shell remains …Chalk: Chalk is a fine-grained, soft, and porous variety of limestone, primarily composed of the microscopic remains of marine plankton. It is often white or light gray and is used for writing, drawing, and as a construction material. Oolitic Limestone: Oolitic limestone consists of small, spherical, or egg-shaped structures called ooids. It ...Rotary lime kiln (rust-colored horizontal tube at right) with preheater, Wyoming, 2010 Traditional lime kiln in Sri Lanka. A lime kiln is a kiln used for the calcination of limestone (calcium carbonate) to produce the form of lime called quicklime (calcium oxide).The chemical equation for this reaction is . CaCO 3 + heat → CaO + CO 2. This reaction can …Chemical Composition and Physical Characteristics of Limestone. Usually, limestone is composed mostly of calcite and sometimes may contain dolomite. It’s common for limestone to contain tiny fragments of shell, fossils, or other debris. Limestone is chalky in appearance and usually white in color with no visible crystals.Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Chemical Composition and Physical Characteristics of Limestone. Usually, limestone is composed mostly of calcite and sometimes may contain dolomite. It’s common for limestone to contain tiny fragments of shell, fossils, or other debris. Limestone is chalky in appearance and usually white in color with no visible crystals.As for the physical properties, limestone usually varies between very fine-textured rocks and coarse-textured rocks. Further, there are many different types and names of limestone like chalk, coquina, travertine, tufa, fossiliferous limestone, lithographic limestone, and oolitic limestone.Chemically-weathered limestone. Rainwater and sea water can act as weak acids. If a coastline is made up of rocks such as limestone or chalk, over time they can become …The Rock Cycle (KS3) | Rocks Around Britain | Sedimentary rocks and scenery | Limestone and chalk. Limestone and chalk. This section shows examples of limestone and chalk …Introducing the world's first line of premium colored chalk, designed specifically with rock climbers, weight lifters, and gymnasts in mind.Chalk – Late Cretaceous limestone. The geological unit The Chalk Group is up to 300 metres (1000’) thick in Dorset but less than 100m in SE Devon due to erosion of most of the sequence. The traditional divisions were Lower Chalk (Cenomanian), Middle Chalk (Turonian) and Upper Chalk (Coniacian to Maastrichtian).The types of Limestone are Chalk, Coquina, Fossiliferous Limestone, Lithographic Limestone, Oolitic Limestone, Travertine, Tufa whereas types of Shale are Red Shale, Black Shale, Green Shale, Grey Shale and Yellow Shale. Streak of rock is the color of powder produced when it is dragged across an unweathered surface.Depositional environment of chalk. Chalk refers to limestone that is formed from the buildup of calcareous shell fragments left behind by small aquatic organisms such as foraminifera. It can also develop from some marine algae’s calcareous remnants. Chalk is an extremely fine-grained, brittle rock that may be readily crumbled or crushed.Hard water is formed when water percolates through deposits of limestone, chalk or gypsum, [1] which are largely made up of calcium and magnesium carbonates, bicarbonates and sulfates . Hard drinking water may have moderate health benefits. It can pose critical problems in industrial settings, where water hardness is monitored to avoid costly ...Chalk. Chalk is a special form of limestone mainly formed in deeper water from the shell remains of microscopic marine plants and animals such as coccolithophores and foraminifera. Unless deeply buried, most chalks are relatively soft rock with a high calcium carbonate content.An umbrella term for many types of sedimentary rock, limestone spans everything from travertine marble to coral reefs to the soft chalk walls of the caves in Champagne, France. Some of the world’s most sought-after wines are made with grapes grown in limestone soils. What is Limestone Soil? Limestone soils are naturally …Many limestone layers also contain fossils of such animals as corals, brachiopods, clams, bryozoans, crinoids, and one-celled fusulinids that were preserved whole or nearly whole. Different types of material form different types limestone. Chalk, for example, is a type of limestone made up mainly of the remains of microorganisms and algae. Pure ... Chalk Limestone. The white sands of The Bahamas archipelago are chalk limestone. This type of rock can be found all over any of the 700 islands that make up The Bahamas. Chalk limestone is very light in color and very hard. It may also be identified by the presence of fossils. It is a type of Biological Limestone.Agricultural lime, also called aglime, agricultural limestone, garden lime or liming, is a soil additive made from pulverized limestone or chalk. The primary active component is calcium carbonate. Additional chemicals vary depending on the mineral source and may include calcium oxide. Unlike the types of lime called quicklime (calcium oxide ...• White Chalk The bones of South Downs are made of chalk limestone, the soft rock formed by the fossilized skeletons of sea creatures that inhabited an ancient ocean here nearly 100 million ...Chemical weathering is the breakdown of rock by changing its chemical composition. When rainwater hits a rock, it decomposes it or eats it away. This is known as carbonation. This occurs when slightly acidic (carbonic) rain or sea water comes into contact with sedimentary rock, such as limestone or chalk, and it causes it to dissolve.Calcium carbonate occurs naturally as chalk, limestone and marble. The photo shows the reaction with marble chips. You get immediate fizzing with a colourless gas given off - that's carbon dioxide. The marble reacts to give a colourless solution of calcium chloride. CaCO 3 (s) + 2HCl(aq) CaCl 2 (aq) + CO 2 (g) + H 2 O(l)09-Feb-2022 ... Chalk is a naturally occurring fine-grained limestone that is formed as a deposit in waters having depth of more than 150 feet.High resolution stone texture of drywall chalk limestone wall cladding. Natural face white rubble stones are laid in horizontal courses with dry joints.Austin Chalk. In Eastern part of Trans-Pecos Texas and High Plains- Chalk and marl; chalk mostly microgranular calcite with minor foraminifera tests and Inoceramun prisms, averages ab out 85 percent calcium carbonate, ledge forming, grayish white, white; alternates with marl, bentonitic seams locally recessive; medium gray; pyrite nodules ...Acid coreflooding has been applied to chalk, dolomite, and limestone carbonate rock samples to measure the efficiency in terms of injected pore volume to breakthrough (PVBT). The rock samples were characterized in terms of porosity, permeability, composition using X-ray diffraction (XRD), and pore distribution using nuclear magnetic resonance ...Chalk: It is white and soft limestone. The rock is made up of microscopic remains of planktonic organisms that live in the surface waters of tropical seas. The friable limestone exhibits an excellent texture. Oolitic limestone: The limestone is formed when calcium carbonate is deposited on the surface of sand grains.Chalk is a variety of limestone composed mainly of calcium carbonate derived from the shells of tiny marine animals known as foraminifera and from the calcareous remains of marine algae known as coccoliths. Chalk is usually white or light gray in color. It is extremely porous, permeable, soft and friable. Benthic Foraminifera: Scanning electron ...Chalk is a sedimentary rock primarily composed of calcium carbonate (calcite). It is formed from the accumulation of microscopic marine organisms' remains, especially coccolithophores. Chalk is known for its distinctive white color, fine-grained texture, and softness. It is commonly associated with marine environments.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 …Chalk Limestone. The white sands of The Bahamas archipelago are chalk limestone. This type of rock can be found all over any of the 700 islands that make up The Bahamas. Chalk limestone is very light in color and very hard. It may also be identified by the presence of fossils. It is a type of Biological Limestone.Coquina is a sedimentary rock composed almost entirely of sand-size fossil debris. The fossils are usually mollusk or gastropod shells and shell fragments. Brachiopod, trilobite, coral, ostracod and other invertebrate shell debris is present in many coquinas. The fossil debris of coquina is composed of calcium carbonate, making coquina a ...May 31, 2022 · Chalk Characteristics and Properties. Chalk, in both its natural and man-made form, is white in colour and is considered to be a fairly soft solid. Naturally, It comes from the ground where it is found as a porous (can hold water) sedimentary rock. It is a form of limestone and is composed of the mineral calcite. cent; limestone, 5.3 percent; and all sedimentary rocks, 8.5 percent. Additional data since the publication of Barrell's summary indicate that the average value of 8.2 percent for the porosity of shale may be low. Athy's graph (1930) for Pennsylvanian and Permian shales from structurally disturbed areas shows an average porosity of 8.822-May-2015 ... Limestone and chalk are sedimentary rocks of organic origin derived from accumulation of corals and shells in the sea. Limestone is a ...Although chalk aquifers are not too often associated with conduit flow, they are highly productive groundwater systems and, like limestone aquifers, they can be vulnerable to contamination when exposed to land use activities. The Danish carbonate rocks are generally recognized to be highly fractured and covered by thick Quaternary sediments. Fissure flow is pronounced, occurring in the upper ...Chalk is a type of limestone made up of the microscopic calcium carbonate shells of marine organisms. Chalk is soft, friable, porous, and effervesces vigorously in contact with …Large limestone deposits from ancient reefs are found inland, such as the exposed limestone in Guadalupe Mountains National Park in New Mexico. Chalk is another form of biochemically produced limestone. Chalk is a soft, porous rock made up of the skeletal parts of microscopic marine organisms. It produces the white cliffs of Dover, England.He enjoys playing sports and watching movies together. See all posts by Travis Thornton. Limestone is a sedimentary carbonate rock. Chalk is a type of limestone. The key difference between limestone and chalk is that the limestone contains both minerals, calcite, and aragonite whereas chalk is a form of limestone which contains calcite.Modern concrete is typically made with portland cement, a mixture of silica sand, limestone, clay, chalk and other ingredients melted together at blistering temperatures. In concrete, this paste binds 'aggregate' - chunks of rock and sand.6. Kilburn White Horse, Yorkshire. Kilburn White Horse (Dreamstime) The largest and most northerly hill figure in England, the Kilburn White Horse was carved into a chalk hill in the North York Moors National Park by a local resident who had been inspired after visiting the White Horse at Uffington.In this study, two limestone quarries, namely Quarry-1 and Quarry-2 were investigated in terms of the Schmidt Hammer Rebound (SHR) distribution. A total of 518 points, i.e., 158 points for Quarry-1 and 360 points for Quarry-2, were tested and evaluated in terms of SHR, respectively. Both quarries were represented with their corresponding …The hardness of Chalk is 1 and that of Limestone is 3-4. The types of Chalk are Not Available whereas types of Limestone are Chalk, Coquina, Fossiliferous Limestone, Lithographic Limestone, Oolitic Limestone, Travertine, Tufa. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Chalk ...Jun 7, 2013 · Calcite is a naturally occurring calcium carbonate (CaO 3) mineral in rocks such as chalk, limestone, and marble. These rocks are the primary sources of the extender pigment. Its whiteness, softness, and fine-grained nature make it an ideal white pigment, both abundant and easily processed. Describe carbonation weathering. When rainwater hits rock it decomposes it or eats it away. This is known as carbonation. This occurs when slightly acidic (carbonic) rain or seawater comes into contact with sedimentary rock, such as limestone or chalk, it causes it to dissolve. A chemical reaction occurs between the acidic water and the …They occur in the form of limestone and chalk, formed from fossils, and marble, formed from the metamorphosis of sedimentary rock. They consist mostly (>98%) of calcium carbonate (CaCO 3), with trace amounts of magnesium carbonate, iron oxide, and aluminum silicates. Dolomite is a blend of calcium and magnesium formed by metamorphosis. Chalk, composed of limestone, represents statues in this activity. Limestone contains calcium carbonate (CaCO 3), which reacts chemically with acids, causing it to deteriorate or erode. The acid causes the calcium (Ca) and carbonate (CO 3) in the limestone to separate into calcium and carbon dioxide gas (CO 2).Chalk. Chalk, a sedimentary rock, is a soft form of limestone that is not well cemented and thus is often powdery and brittle. It usually ranges in color from white to light gray to buff and forms from sediment deposited in a saltwater environment. Composed mostly of the mineral calcite and formed mainly from the remains of floating ...2017, GeoSci Developers. Except where noted, this work is licensed under a Creative Commons Attribution 4.0 International LicenseThe Rock Cycle (KS3) | Rocks Around Britain | Sedimentary rocks and scenery | Limestone and chalk. Limestone and chalk. This section shows examples of limestone and chalk …and carbonate (chalk, limestone, marl) reservoirs. In South Louisiana the formations are younger (Tertiary in age) and the reservoirs are predominantly clastic in nature. Regarding the second point, the northern reservoirs produce oil and abundant gas with large areas producing free gas (e.g. Monroe Gas Field).Oct 12, 2023 · Limestone. Uses of Chalk. Chalk is extremely helpful. Powdered chalk is utilized in toothpaste and stomach medications. Chalk is additionally used to make such items as paint, elastic, and concrete. Craftsmen draw with chalk. Instructors compose on boards with chalk. Be that as it may, the chalk utilized by craftsmen and educators is sometimes ... Cement is manufactured through a closely controlled chemical combination of calcium, silicon, aluminum, iron and other ingredients. Common materials used to manufacture cement include limestone, shells, and chalk or marl combined with shale, clay, slate, blast furnace slag, silica sand, and iron ore. These ingredients, when heated at high ...Limestone Graywacke (Dolostone if has Mg) Precipitation in the deep sea or recrystallization of shells accumulated on the deep sea floor (clastic texture gone). Spherical grains like tiny beads (<2 mm) with concentric laminations. Oolitic Breccia limestone Precipitation in the surf zone near reefs, around fine sand grains, like oystersWhether chalk, limestone, dolomite or marble, all carbonate rocks are subject to erosion. These dissolve under the influence of wind, temperature and water, and the cycle is ready to start anew.In the lime industry, limestone is a general term for rocks that contain 80% or more of calcium or magnesium carbonate, including marble, chalk, oolite, and marl.Further classification is done by composition as high calcium, argillaceous (clayey), silicious, conglomerate, magnesian, dolomite, and other limestones. Uncommon sources of lime …Austin Chalk. Chalk and limestone; hard lime mudstone to soft chalk, glauconitic; marine megafossils common. Only upper 20 to 30 feet present at surface; total thickness about 1,200 feet. Lies below Upson Clay. Age is Late Cretaceous; is oldest unit mapped in this sheet. [Mapped in northwestern Maverick Co., southwestern TX.] Source: Publication.Get ratings and reviews for the top 11 gutter companies in Limestone, IL. 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 valid...To make chalk, limestone is first quarried, generally by an open pit quarry method. Next, the limestone must be crushed. Primary crushing, such as in a jaw crusher, breaks down large boulders; secondary crushing pulverizes smaller chunks into pebbles. 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 ...Many limestone layers also contain fossils of such animals as corals, brachiopods, clams, bryozoans, crinoids, and one-celled fusulinids that were preserved whole or nearly whole. Different types of material form different types limestone. Chalk, for example, is a type of limestone made up mainly of the remains of microorganisms and algae. Pure ... Chalk . Chalk is a soft form of limestone that is light in color. It is formed from the skeletal remains of very small marine organisms such as foraminifera. Coquina . Coquina is a type of limestone that is often formed on beaches as a result of broken shell fragments. Oolitic LimestoneThe State of England’s Chalk Streams report provides a health check for our chalk streams and reveals that over three quarters of them are not in good health. From 2014 to 2017 we led the exciting WaterLIFE project with The Rivers Trust and Westcountry Rivers Trust to improve the health of our rivers. We produced a wealth of guidance, reports ...The chalk is the most porous limestone with a porosity greater than 30%. Although limestone is a soft rock, dense limestone shows a crushing strength of up to 180 MPa. Concrete has a crushing strength of about 40 MPa. Most limestones consist of sand-sized grains in a carbonate mud matrix.A chalk is a soft, friable variety of limestone consisting of poorly lithified calcareous ooze, produced by the accumulation of planktonic organisms in a ...Chalk, limestone, and flint are all examples of sedimentary rocks. Metamorphic rocks are formed when igneous and sedimentary rocks are changed by intense heat or pressure. Marble (from limestone, a sedimentary rock) and granulite (from basalt, an igneous rock) are examples of metamorphic rocks. Ideas for Learning About …Crystal structure of calcite. Calcium carbonate is a chemical compound with the chemical formula Ca CO 3.It is a common substance found in rocks as the minerals calcite and aragonite, most notably in chalk and limestone, eggshells, gastropod shells, shellfish skeletons and pearls.Materials containing much calcium carbonate or resembling it are described as calcareous.An umbrella term for many types of sedimentary rock, limestone spans everything from travertine marble to coral reefs to the soft chalk walls of the caves in Champagne, France. Some of the world’s most sought-after wines are made with grapes grown in limestone soils. What is Limestone Soil? Limestone soils are naturally …Chemically-weathered limestone. Rainwater and sea water can act as weak acids. If a coastline is made up of rocks such as limestone or chalk, over time they can become …Limestone comes in many different varieties. Chalk is a very fine grained, porous marine limestone composed almost entirely of microscopic fossils. Travertine is a freshwater sedimentary limestone that has very thin, crenu-lated layers and is commonly formed at springs. Marble is a carbonate rock, usually a marine limestone, that has been Fossils. The putative galloanseran bird Austinornis lentus has been found in the Austin Chalk. The general absence of dinosaurs is a reflection of the Austin limestone being marine in origin, primarily composed of microscopic shell fragments from floating sea organisms known as "coccolithophores" (the same organisms that contributed to the White Cliffs of Dover, on the south coast of England). Peat Rock Salt (halite) Sandstone Shale Siltstone. Basic Classification - Method of Origin. Clastic. Breccia Conglomerate Sandstone Shale Siltstone. Chemical. Chert Dolomite Gypsum Halite (rock salt) Limestone - micrite Limestone - oolitic Limestone - intraclastic Rock Salt (halite) Biochemical. Chalk Coal - bituminous Coal - anthracite Coquina ... from chalk or limestone rocks. • Chalk is the white rock that forms the ‘white cliffs of Dover’. It is soft and can be used to draw on a blackboard. Hard and soft water • Limestone is a harder grey rock which can form spectacular caves, some of which are open for the public to explore. Both these rocks are made of soluble calcium ...Agricultural lime, also called aglime, agricultural limestone, garden lime or liming, is a soil additive made from pulverized limestone or chalk. The primary active component is calcium carbonate. Additional chemicals vary depending on the mineral source and may include calcium oxide. Unlike the types of lime called quicklime (calcium oxide ... Chalk. Chalk is a soft, white, porous form of limestone. It is relatively resistant to erosion and slumping, compared to the clays with which it is usually associated. Consequently, it forms tall, steep cliffs where chalk ridges meet the sea. Chalk hills, known as chalk downland, usually form where bands of chalk reach the surface at an angle. 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 ...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 ... Coquina is a sedimentary rock composed almost entirely of sand-size fossil debris. The fossils are usually mollusk or gastropod shells and shell fragments. Brachiopod, trilobite, coral, ostracod and other invertebrate shell debris is present in many coquinas. The fossil debris of coquina is composed of calcium carbonate, making coquina a ...The Chalk Group (often just called the Chalk) is the lithostratigraphic unit (a certain number of rock strata) which contains the Upper Cretaceous limestone succession in southern and eastern England. The same or similar rock sequences occur across the wider northwest European chalk 'province'. Chalk definition, a soft, white, powdery limestone consisting chiefly of fossil shells of foraminifers. See more. Sedimentary structures. Sedimentary structures are the larger, generally three-dimensional physical features of sedimentary rocks; they are best seen in outcrop or in large hand specimens rather than through a microscope.Sedimentary structures include features like bedding, ripple marks, fossil tracks and trails, and mud cracks. They …Chalk. A chalk is a soft, friable variety of limestone consisting of poorly lithified calcareous ooze, produced by the accumulation of planktonic organisms in a pelagic (open sea) environment. Chalk is largely made of shells of single-celled marine organisms, such as foraminifera and coccoliths, but fragments of shells of bivalves and ostracods ...Jan 13, 2020 · RAW LIMESTONE CHALK 1" Sedimentary Rock Specimen . Limestone is made up of organic material, primarily calcium carbonate. The chalk variety consists of the shells of coccolithophores, small platy animals that stack together and powder easily. Large layers of chalk indicate a low-oxygen environment, most likely ancient seafloor beds. Limestone. A sedimentary rock composed dominantly of calcium carb, Chalk is a soft, whitish rock. It is a type of limestone . Like other forms of limestone, it is made from animal shells , Eating small amounts of chalk is usually not harmful, according to MedlinePlus. Chalk, a form of limestone, i, Limestone, marble and chalk has CaCO3. The metal refined from this is calcium. Was this answer, Chalk (upper left) is a marine limestone consisting of, Chalk. Chalk is medium-sized stone that combines chiseled looks with the structured simplicity and raw b, 1 Definition. 1.1 Definition. Limestone is a sedimentary rock composed mostly of calcite and aragonite, which are diffe, Secondary School Lower Secondary Grades - Chemistry Useful, A new formula for white paint has given us the whitest whit, Oct 20, 2023 · Austin Chalk. Chalk and limestone; hard lime mudsto, General description. Calcium Carbonate (CaCO 3) is a, A new formula for white paint has given us the whitest w, Organically Formed: Examples include geyserite, chalk, Limestone (calcium carbonate CaCO 3) is a type of car, General description. Calcium Carbonate (CaCO 3) is a nat, May 10, 2020 · Volcanic Wines – the Lava Lover's Dream. Chalk, chalk and up to 120kPa in Grade A (low discontinu-ity) hi, Burning chalk stone was performed in simple kilns in close proximi.