| Calcium is the chemical element in the
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| | by heating and carefully adding water to
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| periodic table that has the symbol Ca and
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| | limestone. When lime is mixed with sand,
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| atomic number 20. Calcium is a soft grey
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| | it hardens into a mortar and is turned
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| alkaline earth metal that is used as a
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| | into plaster by carbon dioxide uptake.
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| reducing agent in the extraction of
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| | Mixed with other compounds, lime forms an
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| thorium, zirconium and uranium. Calcium
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| | important part of Portland cement.
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| is also the fifth most abundant element
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| | When water percolates through limestone
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| in the Earth's crust. It is essential for
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| | or other soluble carbonate rocks, it
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| living organisms, particularly in cell
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| | partially dissolves part of the rock and
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| physiology, and is the most common metal
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| | causes cave formation and characteristic
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| in many animals.
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| | stalactites and stalagmites and also
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| Notable characteristics Calcium is a
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| | forms hard water. Other important calcium
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| rather soft, grey, metallic element that
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| | compounds are nitrate, sulfide, chloride,
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| can be extracted by electrolysis from
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| | carbide, cyanamide, and hypochlorite.
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| calcium fluoride. It burns with a
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| | Isotopes Calcium has four stable isotopes
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| yellow-red flame and forms a white
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| | (40Ca and 42Ca through 44Ca), plus two
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| nitride coating when exposed to air. It
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| | more isotopes (46Ca and 48Ca) that have
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| reacts with water, displacing hydrogen
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| | such long half-lives that for all
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| and forming calcium hydroxide.
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| | practical purposes they can be considered
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| Calcium is essential in muscle
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| | stable.
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| contraction, oocyte activation, building
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| | It also has a cosmogenic isotope,
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| strong bones and teeth, blood clotting,
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| | radioactive 41Ca, which has a half-life
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| nerve impulse transmission, regulating
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| | of 103,000 years. Unlike cosmogenic
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| heartbeat, and fluid balance within
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| | isotopes that are produced in the
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| cells. In the U.S., between about 50% and
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| | atmosphere, 41Ca is produced by neutron
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| 75% of adults do not get sufficient
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| | activation of 40Ca. Most of its
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| calcium in their diet. Adults need
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| | production is in the upper metre or so of
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| between 1,000 and 1,300 mg of calcium in
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| | the soil column where the cosmogenic
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| their daily diet.
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| | neutron flux is still sufficiently
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| The most abundant isotope, 40Ca, has a
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| | strong. 41Ca has received much attention
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| nucleus of 20 protons and 20 neutrons.
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| | in stellar studies because it decays to
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| Its electron configuration is: 2
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| | 41K, a critical indicator of solar-system
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| electrons in the K shell (principal
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| | anomalies.
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| quantum number 1), 8 in the L shell
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| | Naturally occurring calcium is 97% in the
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| (principal quantum number 2), 8 in the M
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| | form of 40Ca. 40Ca is one of the daughter
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| shell (principal quantum number 3), and 2
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| | products of 40K decay, along with 40Ar.
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| in the N shell (principal quantum number
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| | While K-Ar dating has been used
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| 4). The outer shell is the valence shell,
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| | extensively in the geological sciences,
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| with 2 electrons in the lone 4s orbital,
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| | the prevalence of 40Ca in nature has
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| the 3p orbitals being empty.
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| | impeded its use in dating.
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| Occurrence Calcium is not naturally found
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| | Techniques using mass spectrometry and a
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| in its elemental state. Calcium is found
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| | double spike isotope dilution have been
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| mostly in soil systems as limestone,
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| | used for K-Ca age dating.
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| gypsum and fluorite. Stalagmites and
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| | Dietary calcium supplements There are
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| stalactites contain calcium carbonate.
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| | conflicting recommendations about when to
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| Being an essential macromineral in the
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| | take calcium supplements.
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| human diet, soil conservation practices
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| | However, most experts agree that no more
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| often consider the sustainable
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| | than 500 mg should be taken at a time –
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| equilibrium of calcium concentrations in
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| | any excess will go to waste. It is
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| the earth.
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| | recommended to spread doses throughout
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| Applications Calcium is an important
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| | the day, with the last dose near bedtime.
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| component of a healthy diet. A deficit
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| | Recommended daily calcium intake varies
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| can affect bone and tooth formation,
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| | from 1000 to 1500 milligrams, depending
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| while overretention can cause kidney
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| | upon the stage of life.
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| stones. Vitamin D is needed to absorb
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| | Calcium carbonate is the most common and
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| calcium. Dairy products, such as milk and
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| | least expensive calcium supplement. It
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| cheese, are a well-known source of
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| | can be difficult to digest and causes gas
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| calcium. However, some individuals are
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| | in some people. Taking magnesium with it
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| allergic to dairy products and even more
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| | can help to prevent constipation.
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| people, particularly those of
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| | Calcium carbonate is 40% elemental
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| non-European descent, are
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| | calcium. 1000 mg will provides 400 mg of
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| lactose-intolerant, leaving them unable
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| | calcium. Take this supplement with food
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| to consume dairy products.
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| | to aid in absorption.
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| Fortunately, many other good sources of
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| | Calcium citrate is more easily absorbed,
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| calcium exist. These include: seaweeds
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| | easier to digest and less likely to cause
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| such as kelp, wakame and hijiki; nuts and
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| | constipation and gas than calcium
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| seeds (like almonds and sesame); beans;
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| | carbonate. It also has a lower risk of
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| seafood such as oysters and shrimp;
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| | contributing to the formation of kidney
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| soft-boned fish; amaranth; whole wheat;
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| | stones. Calcium citrate is 21% elemental
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| collard greens; okra; rutabaga; broccoli;
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| | calcium. 1000 mg will provide 210 mg of
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| and fortified products such as orange
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| | calcium. It is more expensive than
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| juice and bread.
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| | calcium carbonate and more of it must be
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| Other uses include: as a reducing agent
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| | taken to get the same amount of calcium.
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| in the extraction of other metals, such
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| | Calcium phosphate costs more than calcium
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| as uranium, zirconium, and thorium.
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| | carbonate, but less than calcium citrate.
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| as a deoxidizer, desulfurizer, or
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| | It is easily absorbed and is less likely
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| decarbonizer for various ferrous and
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| | to cause constipation and gas than
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| nonferrous alloys.
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| | either.
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| as an alloying agent used in the
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| | Calcium lactate and calcium aspartate are
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| production of aluminium, beryllium,
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| | both more easily digested, but more
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| copper, lead, and magnesium alloys.
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| | expensive than calcium carbonate.
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| in the making of cements and mortars to
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| | Disorders of calcium metabolism occur
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| be used in construction.
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| | when the body has too little or too much
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| History Calcium (Latin calcis, meaning
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| | calcium. The serum level of calcium is
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| "lime") was known as early as the first
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| | closely regulated within a fairly limited
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| century when the Ancient Romans prepared
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| | range in the human body.
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| lime as calcium oxide. It was not
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| | The amount of biologically active calcium
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| actually isolated until 1808 in England
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| | varies with the level of albumin, a
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| when Sir Humphrey Davy electrolyzed a
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| | protein to which calcium is bound, and
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| mixture of lime and mercuric oxide. Davy
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| | therefore levels of ionized calcium are
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| was trying to isolate calcium and when he
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| | better measures than a total calcium;
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| heard that Berzelius and Pontin prepared
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| | however, one can correct a total calcium
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| calcium amalgam by electrolyzing lime in
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| | if the albumin level is known. When you
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| mercury, he tried it himself. He worked
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| | don't have enough calcium your bones
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| with electrolysis throughout his life and
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| | become weak and very fragile.
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| also discovered/isolated magnesium,
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| | A normal ionized calcium is 1.12-1.45
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| strontium and barium.
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| | mmol/L (4.54-5.61 mg/dL).
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| Compounds Calcium, combined with
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| | A normal total calcium is 2.2-2.6 mmol/L
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| phosphate to form hydroxylapatite, is the
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| | (9-10.5 mg/dl).
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| mineral portion of human and animal bones
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| | Total calcium of less than 8.0 mg/dL is
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| and teeth. The mineral portion of some
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| | hypocalcaemia, with levels below 1.59
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| corals can also be transformed into
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| | mmol/L (6 mg/dL) generally fatal.
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| hydroxylapatite.
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| | Total calcium of more than 11.111 mg/dL
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| Calcium oxide (lime) is used in many
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| | is hypercalcaemia, with levels over 3.753
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| chemical refinery processes and is made
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| | mmol/L (15.12 mg/dL) generally fatal.
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