Sanguine - Red chalk #BC3F4A
56-530: Sanguine ( / ˈ s æ ŋ ɡ w ɪ n / ) or red chalk is chalk of a reddish-brown color, so called because it resembles the color of dried blood . It has been popular for centuries for drawing (where white chalk only works on colored paper). The word comes via French from the Italian sanguigna and originally from the Latin "sanguis". Sanguine lends itself naturally to sketches, life drawings, and rustic scenes. It
112-504: A catalyst's surface area and activity . For example, nickel can be supported on the material—the combination is called Ni–Kieselguhr—to improve its activity as a hydrogenation catalyst. Natural freshwater diatomaceous earth is used in agriculture for grain storage as an anticaking agent , as well as an insecticide. It is approved by the Food and Drug Administration as a feed additive to prevent caking . Some believe it may be used as
168-452: A deposit has not been proven to affect their functionality when it comes to the adsorption of lipids; however, certain applications, such as that for slugs and snails, do work best when a particularly shaped diatom is used, suggesting that lipid adsorption is not the only factor involved. For example, in the case of slugs and snails, large, spiny diatoms work best to lacerate the epithelium of the mollusk. Diatom shells will work to some degree on
224-451: A few are more recent. A mixture of chalk and mercury can be used as fingerprint powder . However, because of the toxicity of the mercury, the use of such mixtures for fingerprinting was abandoned in 1967. Diatomite Diatomaceous earth ( / ˌ d aɪ . ə t ə ˈ m eɪ ʃ ə s / DY -ə-tə- MAY -shəs ), also known as diatomite ( / d aɪ ˈ æ t ə m aɪ t / dy- AT -ə-myte ), celite , or kieselguhr ,
280-589: A mean particle size below about 12 μm (i.e., food grade— see below ). Although considered to be relatively low-risk, pesticides containing diatomaceous earth are not exempt from regulation in the United States under the Federal Insecticide, Fungicide, and Rodenticide Act and must be registered with the Environmental Protection Agency . Its thermal properties enable it to be used as
336-464: A natural anthelmintic (dewormer), although studies have not shown it to be effective. Some farmers add it to their livestock and poultry feed to prevent the caking of feed. "Food-Grade Diatomaceous Earth" is widely available in agricultural feed supply stores. Freshwater diatomite can be used as a growing medium in hydroponic gardens. It is also used as a growing medium in potted plants, particularly as bonsai soil. Bonsai enthusiasts use it as
392-422: A soil additive, or pot a bonsai tree in 100% diatomaceous earth. In vegetable gardening it is sometimes used as a soil conditioner , because like perlite , vermiculite , and expanded clay , it retains water and nutrients, while draining fast and freely, allowing high oxygen circulation within the growing medium. Natural dried, not calcinated diatomaceous earth is regularly used in livestock nutrition research as
448-457: A source of acid-insoluble ash (AIA), which is used as an indigestible marker. By measuring the content of AIA relative to nutrients in test diets and feces or digesta sampled from the terminal ileum (last third of the small intestine) the percentage of that nutrient digested can be calculated using the following equation: where: Natural freshwater diatomaceous earth is preferred by many researchers over chromic oxide, which has been widely used for
504-442: A stabilizing component of dynamite , a thermal insulator , and a soil for potted plants and trees as in the art of bonsai . It is also used in gas chromatography packed columns made with glass or metal as stationary phase. Diatomaceous earth consists of the fossilized remains of diatoms that accumulated over millions of years. It usually comprises 80% to 90% silica, 2% to 4% alumina minerals, and 0.5% to 2% iron oxide, although
560-442: A wide variety of other rock types but lacustrine diatomites are almost always associated with volcanic rock. Diatomaceous chert consists of diatomite that has been cemented with silica. Diatoms are able to extract silica from water that is less than 1% saturated in amorphous silica (saturation index (SI): -2). Their frustules remain undissolved because they are surrounded by an organic matrix. Clay minerals may also precipitate on
616-633: Is mined from chalk deposits both above ground and underground . Chalk mining boomed during the Industrial Revolution , due to the need for chalk products such as quicklime and bricks . Most people first encounter chalk in school where it refers to blackboard chalk , which was originally made of mineral chalk, since it readily crumbles and leaves particles that stick loosely to rough surfaces, allowing it to make writing that can be readily erased. Blackboard chalk manufacturers now may use mineral chalk, other mineral sources of calcium carbonate, or
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#1732859023878672-604: Is 80–90% silica , with 2–4% alumina (attributed mostly to clay minerals ), and 0.5–2% iron oxide . Diatomaceous earth consists of the fossilized remains of diatoms , a type of hard-shelled microalgae , that have accumulated over millions of years. It is used as a filtration aid, mild abrasive in products including metal polishes and toothpaste , mechanical insecticide , absorbent for liquids, matting agent for coatings, reinforcing filler in plastics and rubber, anti-block in plastic films, porous support for chemical catalysts, cat litter , activator in coagulation studies,
728-461: Is a stub . You can help Misplaced Pages by expanding it . Chalk 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 . Chalk is common throughout Western Europe , where deposits underlie parts of France, and steep cliffs are often seen where they meet
784-610: Is a fine-textured, earthy type of limestone distinguished by its light colour, softness, and high porosity. It is composed mostly of tiny fragments of the calcite shells or skeletons of plankton , such as foraminifera or coccolithophores . These fragments mostly take the form of calcite plates ranging from 0.5 to 4 microns in size, though about 10% to 25% of a typical chalk is composed of fragments that are 10 to 100 microns in size. The larger fragments include intact plankton skeletons and skeletal fragments of larger organisms, such as molluscs , echinoderms , or bryozoans . Chalk
840-469: Is a naturally occurring, soft, siliceous sedimentary rock that can be crumbled into a fine white to off-white powder. It has a particle size ranging from more than 3 mm to less than 1 μm , but typically 10 to 200 μm. Depending on the granularity , this powder can have an abrasive feel, similar to pumice powder, and has a low density as a result of its high porosity . The typical chemical composition of oven-dried diatomaceous earth
896-508: Is also the only form of limestone that commonly shows signs of compaction. Flint (a type of chert ) is very common as bands parallel to the bedding or as nodules in seams , or linings to fractures , embedded in chalk. It is probably derived from sponge spicules or other siliceous organisms as water is expelled upwards during compaction. Flint is often deposited around larger fossils such as Echinoidea which may be silicified (i.e. replaced molecule by molecule by flint). Chalk
952-428: Is applied to the hands and feet to remove perspiration and reduce slipping. Chalk may also be used as a house construction material instead of brick or wattle and daub : quarried chalk was cut into blocks and used as ashlar , or loose chalk was rammed into blocks and laid in mortar. There are still houses standing which have been constructed using chalk as the main building material. Most are pre- Victorian though
1008-418: Is as a very mild abrasive and has been used in toothpaste , metal polishes , and some facial scrubs. Diatomite is of value as an insecticide because of its abrasive and physico- sorptive properties. The fine powder adsorbs lipids from the waxy outer layer of the exoskeletons of many species of insects; this layer acts as a barrier that resists the loss of water vapour from the insect's body. Damaging
1064-502: Is available commercially in several formats: In 1866, Alfred Nobel discovered that nitroglycerin could be made much more stable if absorbed in diatomite ( kieselguhr in German). This allowed much safer transport and handling than pure nitroglycerin in liquid form. Nobel patented this mixture as dynamite in 1867; the mixture is also called guhr dynamite in reference to the kieselguhr. The Celle engineer, Wilhelm Berkefeld, recognized
1120-518: Is commonly used as a drying agent to obtain better grip by gymnasts and rock climbers. Glazing putty mainly contains chalk as a filler in linseed oil . Chalk and other forms of limestone may be used for their properties as a base . Chalk is a source of quicklime by thermal decomposition , or slaked lime following quenching of quicklime with water. In agriculture , chalk is used for raising pH in soils with high acidity . Small doses of chalk can also be used as an antacid . Additionally,
1176-510: Is commonly used in lieu of boric acid and can be used to help control and possibly eliminate bed bugs , house dust mite , cockroach , ant , and flea infestations. Diatomaceous earth is widely applied for insect control in grain storage. It is used to control cannibalistic behaviors in confused flour beetles , which infest flour storages. In order to be effective as an insecticide, diatomaceous earth must be uncalcinated (i.e., it must not be heat-treated prior to application) and have
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#17328590238781232-489: Is dependent upon the age and paleoecology of the deposit. In turn, the shape of a diatom is determined by its species. Many deposits throughout British Columbia , such as Red Lake Earth, are from the Miocene epoch and contain a species of diatom known as Melosira granulata . These diatoms have a small globular shape. A deposit containing diatoms from this epoch can provide certain benefits over others. For example, diatoms from
1288-711: Is ideal for rendering modeling and volume, and human flesh. In the form of wood-cased pencils and manufactured sticks, sanguine may be used similarly to charcoal and pastel. As with pastel, a mid-toned paper may be put to good use. A fixative may be applied to preserve the finished state of the drawing. The pigment used in sanguine sticks comes from red earths such as red ochre . Sanguines are also available in several other tones such as orange, tan, brown, beige. Red chalk: material, history and application in art, J.den Hollander Red chalk: map of historic mining sites with references to sources, J.den Hollander, B.Reissland, N.Wichern, I.Joosten (2019) This art -related article
1344-571: Is now usually made of talc (magnesium silicate). Chalk beds form important petroleum reservoirs in the North Sea and along the Gulf Coast of North America. In southeast England, deneholes are a notable example of ancient chalk pits. Such bell pits may also mark the sites of ancient flint mines, where the prime object was to remove flint nodules for stone tool manufacture. The surface remains at Cissbury are one such example, but perhaps
1400-586: Is so common in Cretaceous marine beds that the Cretaceous Period was named for these deposits. The name Cretaceous was derived from Latin creta , meaning chalk . Some deposits of chalk were formed after the Cretaceous. The Chalk Group is a European stratigraphic unit deposited during the late Cretaceous Period. It forms the famous White Cliffs of Dover in Kent , England, as well as their counterparts of
1456-401: Is typically almost pure calcite, CaCO 3 , with just 2% to 4% of other minerals. These are usually quartz and clay minerals , though collophane (cryptocrystalline apatite , a phosphate mineral) is also sometimes present, as nodules or as small pellets interpreted as fecal pellets. In some chalk beds, the calcite has been converted to dolomite , CaMg(CO 3 ) 2 , and in a few cases
1512-453: Is used in chemistry as a filtration aid, to increase flow rate, and filter very fine particles that would otherwise pass through or clog filter paper . It is also used to filter water, particularly in the drinking water treatment process and in fish tanks , and other liquids, such as beer and wine. It can also filter syrups, sugar, and honey without removing or altering their color, taste, or nutritional properties. The oldest use of diatomite
1568-502: Is used in some home products where dryness or the ability to wick away moisture is critical. In particular there are bath mats made of DE which absorb water from the bather and allow it to spread the material and rapidly evaporate away. There are also spoons made of DE for scooping sugar and other hydroscopic kitchen ingredients. Certain species of bacteria in oceans and lakes can accelerate the rate of dissolution of silica in dead and living diatoms by using hydrolytic enzymes to break down
1624-723: The Cap Blanc Nez on the other side of the Dover Strait . The Champagne region of France is mostly underlain by chalk deposits, which contain artificial caves used for wine storage . Some of the highest chalk cliffs in the world occur at Jasmund National Park in Germany and at Møns Klint in Denmark . Chalk deposits are also found in Cretaceous beds on other continents, such as the Austin Chalk , Selma Group , and Niobrara Formations of
1680-537: The Eocene epoch are not as effective in their ability to absorb fluids because as older diatoms recrystallize, their small pores become filled with silica. Diatomite forms by the accumulation of the amorphous silica ( opal , SiO 2 · n H 2 O ) remains of dead diatoms (microscopic single-celled algae ) in lake sediment or marine sediments . The fossil remains consist of a pair of symmetrical shells or frustules . Marine diatomites are found in association with
1736-769: The Southern California coast . This is the world's largest deposit of diatomite. Additional marine deposits have been worked in Maryland , Virginia , Algeria and the MoClay of Denmark. Freshwater lake deposits occur in Nevada, Oregon , Washington and California . Lake deposits also occur in interglacial lakes in the eastern United States, in Canada and in Europe in Germany, France, Denmark and
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1792-614: The Czech Republic. The worldwide association of diatomite deposits and volcanic deposits suggests that the availability of silica from volcanic ash may be necessary for thick diatomite deposits. Diatomaceous earth is sometimes found on desert surfaces. Research has shown that the erosion of diatomaceous earth in such areas (such as the Bodélé Depression in the Sahara ) is one of the most important sources of climate-affecting dust in
1848-698: The North American interior. Chalk is also found in western Egypt (Khoman Formation) and western Australia ( Miria Formation ). Chalk of Oligocene to Neogene age has been found in drill cores of rock under the Pacific Ocean at Stewart Arch in the Solomon Islands . There are layers of chalk, containing Globorotalia , in the Nicosia Formation of Cyprus , which formed during the Pliocene . Chalk
1904-555: The ability of the diatomaceous earth to filter and developed tubular filters (known as filter candles) fired from diatomaceous earth. During the cholera epidemic in Hamburg in 1892, these Berkefeld filters were used successfully. One form of diatomaceous earth is used as a filter medium, especially for swimming pools. It has a high porosity because it is composed of microscopically small, hollow particles. Diatomaceous earth (sometimes referred to by trademarked brand names such as Celite)
1960-546: The atmosphere. The siliceous frustules of diatoms accumulate in fresh and brackish wetlands and lakes. Some peats and mucks contain a sufficient abundance of frustules such that they can be mined. Most of Florida's diatomaceous earths have been found in the muck of wetlands or lakes. The American Diatomite Corporation, from 1935 to 1946, refined a maximum of 145 tons per year from their processing plant near Clermont, Florida . Muck from several locations in Lake County, Florida
2016-408: The barrier material in some fire-resistant safes. It is also used in evacuated powder insulation for use with cryogenics. Diatomaceous earth powder is inserted into the vacuum space to aid in the effectiveness of vacuum insulation. It was used in the classical AGA cookers as a thermal heat barrier. Diatomaceous earth also finds some use as a support for catalysts , generally serving to maximize
2072-614: The calcined form had developed pneumoconiosis . Today's standard diatomaceous earth formulations are safer to use, as they are predominantly made up of amorphous silica and contain little or no crystalline silica. The crystalline silica content of diatomaceous earth is regulated in the United States by the Occupational Safety and Health Administration (OSHA). There are guidelines from the National Institute for Occupational Safety and Health that set maximum amounts allowable in
2128-548: The chalk came mostly form low-magnesium calcite skeletons, so the sediments were already in the form of highly stable low-magnesium calcite when deposited. This is in contrast with most other limestones, which formed from high-magnesium calcite or aragonite that rapidly converted to the more stable low-magnesium calcite after deposition, resulting in the early cementation of such limestones. In chalk, absence of this calcium carbonate conversion process prevented early cementation, which partially accounts for chalk's high porosity. Chalk
2184-485: The dolomitized chalk has been dedolomitized back to calcite. Chalk is highly porous, with typical values of porosity ranging from 35 to 47 per cent. While it is similar in appearance to both gypsum and diatomite , chalk is identifiable by its hardness, fossil content, and its reaction to acid (it produces effervescence on contact). In Western Europe, chalk was formed in the Late Cretaceous Epoch and
2240-437: The early Palaeocene Epoch (between 100 and 61 million years ago). It was deposited on extensive continental shelves at depths between 100 and 600 metres (330 and 1,970 ft), during a time of nonseasonal (likely arid) climate that reduced the amount of erosion from nearby exposed rock. The lack of nearby erosion explains the high purity of chalk. The coccolithophores, foraminifera, and other microscopic organisms from which
2296-532: The entire worldwide production of diatomaceous earth was from this region. In Poland diatomaceous earth deposits are found in Jawornik, and are composed mostly of diatomaceous skeletons (frustules). In Germany, diatomaceous earth was also extracted at Altenschlirf on the Vogelsberg ( Upper Hesse ) and at Klieken ( Saxony-Anhalt ). There is a layer of diatomaceous earth more than 6 meters (20 ft) thick in
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2352-399: The frustules and protect them from dissolution in sea water. When the diatom dies, the frustule is stripped of its organic layer and exposed to sea water. As a result, only 1% to 10% of frustules survive long enough to be buried under sediments and some of this is dissolved within the sediments. Only an estimated 0.05% to 0.15% of the original amount of silica produced by diatoms is preserved in
2408-417: The layer increases the evaporation of water from their bodies, so that they dehydrate, often fatally. This also works against gastropods and is commonly employed in gardening to defeat slugs . However, since slugs inhabit humid environments, efficacy is very low. Diatomaceous earth is sometimes mixed with an attractant or other additives to increase its effectiveness. The shape of the diatoms contained in
2464-409: The lungs, causing silicosis . Amorphous silica is considered to have low toxicity, but prolonged inhalation causes lung changes. Diatomaceous earth is mainly amorphous silica but contains some crystalline silica, especially in the saltwater forms. In a 1978 study of workers, those exposed to natural diatomaceous earth for over five years had no significant lung changes while 40% of those exposed to
2520-528: The mineral gypsum ( calcium sulfate ). While gypsum-based blackboard chalk is the lowest cost to produce, and thus widely used in the developing world , use of carbonate-based chalk produces larger particles and thus less dust, and it is marketed as "dustless chalk". Coloured chalks, pastel chalks, and sidewalk chalk (shaped into larger sticks and often coloured), used to draw on sidewalks , streets, and driveways , are primarily made of gypsum rather than calcium carbonate chalk. Magnesium carbonate chalk
2576-557: The most famous is the extensive complex at Grimes Graves in Norfolk . Chalk was traditionally used in recreation. In field sports, such as tennis played on grass, powdered chalk was used to mark the boundary lines of the playing field or court. If a ball hits the line, a cloud of chalk or pigment dust will be visible. In recent years, powdered chalk has been replaced with titanium dioxide . In gymnastics, rock-climbing, weightlifting and tug of war , chalk — now usually magnesium carbonate —
2632-621: The nature reserve of Soos in the Czech Republic. Deposits on the Isle of Skye , off the west coast of Scotland, were mined until 1960. In Colorado and in Clark County, Nevada , United States, there are deposits that are up to several hundred meters thick in places. Marine deposits have been worked in the Sisquoc Formation in Santa Barbara County, California near Lompoc and along
2688-521: The organic algal material. The Earth's climate is affected by dust in the atmosphere , so locating major sources of atmospheric dust is important for climatology . Recent research indicates that surface deposits of diatomaceous earth play an important role. Research shows that significant dust comes from the Bodélé Depression in Chad , where storms push diatomite gravel over dunes , generating dust by abrasion . Inhalation of crystalline silica harms
2744-400: The precise composition of every deposit is different. Deposits may contain different amounts of silica depending on the sedimentation conditions , the presence of other sediments (clay, sand, volcanic ashes), and the age of the deposit ( diagenesis , silica (SiO 2 ) dissolution/precipitation, diatoms tests ageing). The species of diatom may also differ among deposits. The species of diatom
2800-411: The product (1%) and in the air near the breathing zone of workers, with a recommended exposure limit at 6 mg/m over an 8-hour workday. OSHA has set a permissible exposure limit for diatomaceous earth as 20 mppcf (80 mg/m /%SiO 2 ). At levels of 3,000 mg/m , diatomaceous earth is immediately dangerous to life and health. In the 1930s, long-term occupational exposure among workers in
2856-505: The same purpose, the latter being a known carcinogen and, therefore, a potential hazard to research personnel. Spent diatomaceous earth from the brewing process can be added to ceramic mass for the production of red bricks with higher open porosity. Diatomaceous earth is considered a very prominent inorganic non-metallic material that can be used for the production of various ceramics, including production of porous ceramics under low temperature hydrothermal technology. Diatomaceous earth
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#17328590238782912-551: The sea in places such as the Dover cliffs on the Kent coast of the English Channel . Chalk is mined for use in industry, such as for quicklime , bricks and builder's putty , and in agriculture , for raising pH in soils with high acidity . It is also used for " blackboard chalk " for writing and drawing on various types of surfaces, although these can also be manufactured from other carbonate-based minerals, or gypsum . Chalk
2968-572: The sedimentary record. In 1836 or 1837, German peasant Peter Kasten discovered diatomaceous earth (German: Kieselgur ) when sinking a well on the northern slopes of the Haußelberg hill, on Lüneburg Heath in North Germany . The extraction site on Lüneburg Heath was 1863–1994 Neuohe, while the storage sites were: The deposits are up to 28 meters (92 ft) thick and are all of freshwater diatomaceous earth. Until World War I , almost
3024-436: The small particles of chalk make it a substance ideal for cleaning and polishing. For example, toothpaste commonly contains small amounts of chalk, which serves as a mild abrasive . Polishing chalk is chalk prepared with a carefully controlled grain size, for very fine polishing of metals. French chalk (also known as tailor's chalk) is traditionally a hard chalk used to make temporary markings on cloth, mainly by tailors . It
3080-416: The vast majority of animals that undergo ecdysis in shedding cuticle , such as arthropods or nematodes . It also may have other effects on lophotrochozoans , such as mollusks or annelids . Medical-grade diatomite has been studied for its efficacy as a deworming agent in cattle; in both studies cited the groups being treated with diatomaceous earth did not fare any better than control groups. It
3136-747: Was dried and burned ( calcined ) to produce the diatomaceous earth. It was formerly extracted from Lake Mývatn in Iceland. The commercial deposits of diatomite are restricted to Tertiary or Quaternary periods. Older deposits from as early as the Cretaceous Period are known, but are of low quality. Diatomite deposits rich in fossils have been located in New Zealand, but mining of the Foulden Maar deposits on an industrial scale, for conversion to animal feed, has drawn strong opposition. Diatomaceous earth
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