"Calcium Calcium is a chemical element with symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust and the third most abundant metal, after iron and aluminium. The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossilised remnants of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. The"
"elements in Earth's crust, having an average mass fraction of 0.001 ppm in crustal rock; platinum is 10 times more abundant, gold is 40 times more abundant, and silver and mercury are 80 times more abundant. Tellurium is about as abundant as iridium. In contrast to its low abundance in crustal rock, iridium is relatively common in meteorites, with concentrations of 0.5 ppm or more. The overall concentration of iridium on Earth is thought to be much higher than what is observed in crustal rocks, but because of the density and siderophilic (""iron-loving"") character of iridium, it descended below the"
"iron 5.6%, calcium 4.2%, sodium 2.5%, magnesium 2.4%, potassium 2.0%, and titanium 0.61%. Other elements occur at less than 0.15%. For a complete list, see abundance of elements in Earth's crust. The graph at right illustrates the relative atomic-abundance of the chemical elements in Earth's upper continental crust— the part that is relatively accessible for measurements and estimation. Many of the elements shown in the graph are classified into (partially overlapping) categories: Note that there are two breaks where the unstable (radioactive) elements technetium (atomic number 43) and promethium (atomic number 61) would be. These elements are surrounded by stable"
"have larger ionic radii) and therefore more strongly concentrated in the continental crust than the heavier rare earth elements. In most rare earth ore deposits, the first four rare earth elements – lanthanum, cerium, praseodymium, and neodymium – constitute 80% to 99% of the total amount of rare earth metal that can be found in the ore. The mass-abundance of the eight most abundant elements in the Earth's mantle (see main article above) is approximately: oxygen 45%, magnesium 23%, silicon 22%, iron 5.8%, calcium 2.3%, aluminum 2.2%, sodium 0.3%, potassium 0.3%. The mantle differs in elemental composition from the crust"
"up approximately 2.6% of the Earth's crust measured by weight, making it the sixth most abundant element overall and the most abundant alkali metal. Potassium makes up approximately 1.5% of the Earth's crust and is the seventh most abundant element. Sodium is found in many different minerals, of which the most common is ordinary salt (sodium chloride), which occurs in vast quantities dissolved in seawater. Other solid deposits include halite, amphibole, cryolite, nitratine, and zeolite. Many of these solid deposits occur as a result of ancient seas evaporating, which still occurs now in places such as Utah's Great Salt Lake"
"of uranium and thorium. Oxygen and silicon are notably the most common elements in the crust. On Earth and in rocky planets in general, silicon and oxygen are far more common than their cosmic abundance. The reason is that they combine with each other to form silicate minerals. In this way, they are the lightest of all of the two-percent ""astronomical metals"" (i.e., non-hydrogen and helium elements) to form a solid that is refractory to the Sun's heat, and thus cannot boil away into space. All elements lighter than oxygen have been removed from the crust in this way. ""Rare"""
"earth's crust at a concentration of two to six parts per million (ppm), much of which is in soils, where it has a concentration of six ppm. Beryllium is one of the rarest elements in seawater, even rarer than elements such as scandium, with a concentration of 0.2 parts per trillion. However, in freshwater, beryllium is somewhat more common, with a concentration of 0.1 parts per billion. Magnesium and calcium are very common in the earth's crust, being respectively the fifth- eighth-most-abundant elements. None of the alkaline earth metals are found in their elemental state. Common magnesium--containing minerals are carnallite,"
"°C respectively are the second-highest among all the metalloids and nonmetals, being only surpassed by boron. Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure element in the Earth's crust. It is most widely distributed in dusts, sands, planetoids, and planets as various forms of silicon dioxide (silica) or silicates. More than 90% of the Earth's crust is composed of silicate minerals, making silicon the second most abundant element in the Earth's crust (about 28% by mass) after oxygen. Most silicon is used commercially without being separated, and often with"
"was its ability to form compounds with hydrogen. Under these conditions, the s- and f-block metals were strongly enriched during the formation of the Earth. The most enriched elements are rubidium, strontium and barium, which between them account for over 50 percent by mass of all elements heavier than iron in the Earth's crust. The nonmetallic lithophiles – phosphorus and the halogens – exist on Earth as ionic salts with s-block metals in pegmatites and seawater. With the exception of fluorine, whose hydride forms hydrogen bonds and is therefore of relatively low volatility, these elements have had their concentrations on"
"Earth's crust, quartz (SiO) is the most abundant mineral species. It is characterized by its high chemical and physical resistivity. Quartz has several polymorphs, including tridymite and cristobalite at high temperatures, high-pressure coesite, and ultra-high pressure stishovite. The latter mineral can only be formed on Earth by meteorite impacts, and its structure has been composed so much that it had changed from a silicate structure to that of rutile (TiO). The silica polymorph that is most stable at the Earth's surface is α-quartz. Its counterpart, β-quartz, is present only at high temperatures and pressures (changes to α-quartz below 573 °C"
"titanium, zirconium and hafnium, the abundance decreases with increase of atomic mass. Titanium is the seventh most abundant metal in Earth's crust and has an abundance of 6320 ppm, while zirconium has an abundance of 162 ppm and hafnium has only an abundance of 3 ppm. All three stable elements occur in heavy mineral sands ore deposits, which are placer deposits formed, most usually in beach environments, by concentration due to the specific gravity of the mineral grains of erosion material from mafic and ultramafic rock. The titanium minerals are mostly anatase and rutile, and zirconium occurs in the mineral"
"element estimated to average 3 parts per million in the Earth's crust. It is the 45th most abundant element and the 36th among the metals. Nevertheless, it is more abundant than such elements as antimony, cadmium, tin, and tungsten, and two orders of magnitude more abundant than mercury and silver; it is 3.3% as abundant as rubidium, with which it is closely associated, chemically. Due to its large ionic radius, caesium is one of the ""incompatible elements"". During magma crystallization, caesium is concentrated in the liquid phase and crystallizes last. Therefore, the largest deposits of caesium are zone pegmatite ore"
"represented by stars, planets and living beings. The balance is made of dark energy and dark matter, both of which are poorly understood at present. Hydrogen, carbon, nitrogen, and oxygen constitute the great bulk of the Earth's atmosphere, oceans, crust, and biosphere; the remaining nonmetals have abundances of 0.5 per cent or less. In comparison, 35 per cent of the crust is made up of the metals sodium, magnesium, aluminium, potassium and iron; together with a metalloid, silicon. All other metals and metalloids have abundances within the crust, oceans or biosphere of 0.2 per cent or less. Nonmetals, and metalloids,"
"Uranium is a naturally occurring element that can be found in low levels within all rock, soil, and water. Uranium is the 51st element in order of abundance in the Earth's crust. Uranium is also the highest-numbered element to be found naturally in significant quantities on Earth and is almost always found combined with other elements. The decay of uranium, thorium, and potassium-40 in the Earth's mantle is thought to be the main source of heat that keeps the outer core liquid and drives mantle convection, which in turn drives plate tectonics. Uranium's average concentration in the Earth's crust is"
"Earth as a whole (behind iron, oxygen and silicon), making up 13% of the planet's mass and a large fraction of planet's mantle. The relative abundance of magnesium is related to the fact that it is easily built up in supernova stars from a sequential addition of three helium nuclei to carbon (which in turn is made from three helium nuclei). Due to magnesium ion's high solubility in water, it is the third most abundant element dissolved in seawater. The free element (metal) is not found naturally on Earth, as it is highly reactive (though once produced, it is coated"
"the magnesium is expelled into the interstellar medium where it may recycle into new star systems. Magnesium is the eighth most abundant element in the Earth's crust and the fourth most common element in the Earth (after iron, oxygen and silicon), making up 13% of the planet's mass and a large fraction of the planet's mantle. It is the third most abundant element dissolved in seawater, after sodium and chlorine. Magnesium occurs naturally only in combination with other elements, where it invariably has a +2 oxidation state. The free element (metal) can be produced artificially, and is highly reactive (though"
"the 19th century. Mercury is an extremely rare element in Earth's crust, having an average crustal abundance by mass of only 0.08 parts per million (ppm). Because it does not blend geochemically with those elements that constitute the majority of the crustal mass, mercury ores can be extraordinarily concentrated considering the element's abundance in ordinary rock. The richest mercury ores contain up to 2.5% mercury by mass, and even the leanest concentrated deposits are at least 0.1% mercury (12,000 times average crustal abundance). It is found either as a native metal (rare) or in cinnabar, metacinnabar, corderoite, livingstonite and other"
"up 1.5 parts per million of the earth's crust, making it the 53rd most abundant element there. The soils contain 1 to 10 parts per million of arsenic, and seawater contains 1.6 parts per billion of arsenic. Arsenic makes up 100 parts per billion of a typical human by weight. Some arsenic exists in elemental form, but most arsenic is found in the arsenic minerals orpiment, realgar, arsenopyrite, and enargite. Antimony makes up 0.2 parts per million of the earth's crust, making it the 63rd most abundant element there. The soils contain 1 part per million of antimony on average,"
"aluminum. Although no chalcophile element is of high abundance in the Earth's crust, chalcophile elements constitute the bulk of commercially important metals. This is because, whereas lithophile elements require energy-intensive electrolysis for extraction, chalcophiles can be easily extracted by reduction with coke, and chalcophiles' geochemical concentration – which in extreme cases can exceed 100,000 times average crustal abundance. These greatest enrichments occur in high plateaux like the Tibetan Plateau and the Bolivian altiplano where large quantities of chalcophile elements have been uplifted through plate collisions. A side-effect of this in modern times is that the rarest chalcophiles (like mercury) are"
"Family, Tribe, Genus, and Species. The abundance and diversity of minerals is controlled directly by their chemistry, in turn dependent on elemental abundances in the Earth. The majority of minerals observed are derived from the Earth's crust. Eight elements account for most of the key components of minerals, due to their abundance in the crust. These eight elements, summing to over 98% of the crust by weight, are, in order of decreasing abundance: oxygen, silicon, aluminium, iron, magnesium, calcium, sodium and potassium. Oxygen and silicon are by far the two most important – oxygen composes 47% of the crust by"
"flares where a brilliant white light is required. It was also used for various theatrical effects, such as lightning, pistol flashes, and supernatural appearances. Magnesium is the eighth-most-abundant element in the Earth's crust by mass and tied in seventh place with iron in molarity. It is found in large deposits of magnesite, dolomite, and other minerals, and in mineral waters, where magnesium ion is soluble. Although magnesium is found in more than 60 minerals, only dolomite, magnesite, brucite, carnallite, talc, and olivine are of commercial importance. The cation is the second-most-abundant cation in seawater (about ⅛ the mass of sodium"
"since decayed and no longer contribute. In the Earth's crust, thorium is much more abundant: with an abundance of 8.1 parts per million (ppm), it is one of the most abundant of the heavy elements, almost as abundant as lead (13 ppm) and more abundant than tin (2.1 ppm). This is because thorium is likely to form oxide minerals that do not sink into the core; it is classified as a lithophile. Common thorium compounds are also poorly soluble in water. Thus, even though the Earth contains the same abundances of the elements as the Solar System as a whole,"
"an environment due to rapid leaching. Aluminum is the most common metal found in the Earth's crust. It is found in all soils and in all environments, from temperate to tropical. In a soluble state, it is highly toxic to plant life, as it inhibits root growth; however, in neutral and alkaline soils common to the temperate zones, it is insoluble and therefore inert. Soil fertility is directly influenced by how acidic it is, as the more acidic, the higher the level of aluminum toxicity; in areas where the pH drops below 5, aluminum becomes soluble and can enter into"
"krypton-82. Rubidium is the twenty-third most abundant element in the Earth's crust, roughly as abundant as zinc and rather more common than copper. It occurs naturally in the minerals leucite, pollucite, carnallite, and zinnwaldite, which contain as much as 1% rubidium oxide. Lepidolite contains between 0.3% and 3.5% rubidium, and is the commercial source of the element. Some potassium minerals and potassium chlorides also contain the element in commercially significant quantities. Seawater contains an average of 125 µg/L of rubidium compared to the much higher value for potassium of 408 mg/L and the much lower value of 0.3 µg/L for"
"Earth significantly reduced through escape of volatile hydrides during the Earth's formation. Although they are present in the Earth's crust in concentrations quite close to their solar abundances, phosphorus and the heavier halogens are probably significantly depleted ""on Earth as a whole"" relative to their solar abundances. Several transition metals, including chromium, molybdenum, iron and manganese, show ""both"" lithophile ""and"" siderophile characteristics and can be found in both these two layers. Although these metals form strong bonds with oxygen and are never found in the Earth's crust in the free state, metallic forms of these elements are thought very likely"
"amounts of nickel (5.8%), sulfur (4.5%), and less than 1% trace elements. The alkali metals, due to their high reactivity, do not occur naturally in pure form in nature. They are lithophiles and therefore remain close to the Earth's surface because they combine readily with oxygen and so associate strongly with silica, forming relatively low-density minerals that do not sink down into the Earth's core. Potassium, rubidium and caesium are also incompatible elements due to their large ionic radii. Sodium and potassium are very abundant in earth, both being among the ten most common elements in Earth's crust; sodium makes"
"earth elements is a historical misnomer. The persistence of the term reflects unfamiliarity rather than true rarity. The more abundant rare earth elements are similarly concentrated in the crust compared to commonplace industrial metals such as chromium, nickel, copper, zinc, molybdenum, tin, tungsten, or lead. The two least abundant rare earth elements (thulium and lutetium) are nearly 200 times more common than gold. However, in contrast to the ordinary base and precious metals, rare earth elements have very little tendency to become concentrated in exploitable ore deposits. Consequently, most of the world's supply of rare earth elements comes from only"
"alpha decay. The atomic mass of tellurium (127.60 g·mol) exceeds that of iodine (126.90 g·mol), the next element in the periodic table. With an abundance in the Earth's crust comparable to that of platinum (about 1 µg/kg), tellurium is one of the rarest stable solid elements. In comparison, even the rarest of the stable lanthanides have crustal abundances of 500 µg/kg (see Abundance of the chemical elements). This rarity of tellurium in the Earth's crust is not a reflection of its cosmic abundance. Tellurium is more abundant than rubidium in the cosmos, though rubidium is 10,000 times more abundant in"
"the Earth's crust relative to their solar abundances, though because the minerals they form are nonmetallic, this depletion has not reached the levels found with siderophile elements. However, because they formed volatile hydrides on the primitive Earth when the controlling redox reaction was the oxidation or reduction of hydrogen, the less metallic chalcophile elements are strongly depleted on Earth as a whole relative to cosmic abundances. This is most especially true of the chalcogens selenium and tellurium (which formed volatile hydrogen selenide and hydrogen telluride, respectively), which for this reason are among the rarest elements found in the Earth's crust"
"point of nitrogen. Yttrium is found in most rare-earth minerals, it is found in some uranium ores, but is never found in the Earth's crust as a free element. About 31 ppm of the Earth's crust is yttrium, making it the 28th most abundant element, 400 times more common than silver. Yttrium is found in soil in concentrations between 10 and 150 ppm (dry weight average of 23 ppm) and in sea water at 9 ppt. Lunar rock samples collected during the American Apollo Project have a relatively high content of yttrium. Yttrium has no known biological role, though it"
"of elements heavier than helium in the interstellar medium. When gravitational attraction causes this matter to coalesce and collapse new stars and planets are formed. The Earth's crust is made of approximately 5% of heavy metals by weight, with iron comprising 95% of this quantity. Light metals (~20%) and nonmetals (~75%) make up the other 95% of the crust. Despite their overall scarcity, heavy metals can become concentrated in economically extractable quantities as a result of mountain building, erosion, or other geological processes. Heavy metals are primarily found as lithophiles (rock-loving) or chalcophiles (ore-loving). Lithophile heavy metals are mainly f-block"
"magnesite, and dolomite. Common calcium-containing minerals are chalk, limestone, gypsum, and anhydrite. Strontium is the fifteenth-most-abundant element in the Earth's crust. The principal minerals are celestite and strontianite. Barium is slightly less common, much of it in the mineral barite. Radium, being a decay product of uranium, is found in all uranium-bearing ores. Due to its relatively short half-life, radium from the Earth's early history has decayed, and present-day samples have all come from the much slower decay of uranium. Most beryllium is extracted from beryllium hydroxide. One production method is sintering, done by mixing beryl, sodium fluorosilicate, and soda"
"elements formed with a supernova or similarly cataclysmic event. Iron and nickel are the most abundant metals in metallic meteorites and in the dense metal cores of planets such as Earth. Nickel–iron alloys occur naturally on Earth's surface as telluric or meteoric iron. The affinity of nickel atoms (atomic number 28) for iron (atomic number 26) results in natural occurring alloys and a large number of commercial alloys, and provides a complex electron environment for catalyzing chemical reactions. In steel metallurgy, nickel is alloyed with iron to produce maraging steel and some low-alloy steels. Other technological uses include Invar and"