A variety of celestite containing calcium. Standard, 2
A monoclinic mineral, Ca4 Fe(Fe,Al)4 (PO4 )6
(OH)4 .13H2 O ; occurs in scales and nodules.
See:tyuyamunite
An orthorhombic mineral, CaCu(VO4 )(OH) ; adelite group; moderately
radioactive; in the Colorado Plateau in sandstone associated with
carnotite and tyuyamunite, or in the oxidized zone of deposits containing
vanadium minerals.
A limestone consisting predominantly of detrital calcite particles of silt
size; a consolidated calcareous silt. AGI
a. A trigonal mineral, 4[CaCO3 ] ; has prolific crystal habits,
rhombohedral cleavage; defines hardness 3 on the Mohs scale; effervesces
readily in dilute hydrochloric acid; a common and widely distributed
rock-forming, authigenic, biogenic, and vein mineral; raw material for
Portland cement, agricultural lime, flux for ore reduction, dimension
stone, and concrete aggregate; the major mineral in limestone, marble,
chalk, spongy tufa, cave deposits, and carbonatite; a cementing mineral in
many clastic sedimentary rocks; a minor mineral in some silicate igneous
and metamorphic rocks. Coarsely crystalline varieties are called nailhead
spar, dogtooth spar (acute scalenohedra), and Iceland spar (optical-grade
crystals). Abbrev.: Cc. CF:dolomite
calcspar.
b. The mineral group calcite, gaspeite, magnesite, otavite, rhodochrosite,
siderite, smithsonite, and sphaerocobaltite
A limestone containing not more than 5% of magnesium carbonate.
A crystalline variety of limestone containing not more than 5% of
magnesium carbonate.
A dolomite rock in which calcite is conspicuous, but the mineral dolomite
is more abundant; specif. a dolomite rock containing 10% to 50% calcite
and 50% to 90% dolomite, or a dolomite rock whose Ca/Mg ratio ranges from
2.0 to 3.5. CF:dolomitic limestone
A rock composed of calcite; e.g., limestone.
a. The act or process of forming calcite, such as by alteration of
aragonite. AGI
b. The alteration of existing rocks to limestone, due to the replacement
of mineral particles by calcite; e.g., of dolomite in dolomite rocks or of
feldspar and quartz in sandstones. AGI
Refractory; said of certain ores. Fay
A metallic element of the alkaline-earth group; never found in nature
uncombined, occurs abundantly as limestone (CaCO3 ), gypsum (CaSO
4 . 2H2 O), and fluorite (CaF2 ). Symbol, Ca. Used as
a reducing agent, deoxidizer, desulfurizer, or decarburizer for alloys; as
quicklime (CaO), it is the great cheap base of the chemical industry with
countless uses. Handbook of Chemistry and Physics, 3
Artificially prepared autunite in which calcium can be replaced by Na, K,
Ba, Mn, Cu, Ni, Co, and Mg. Syn:autunite
CaC2 ; produced commercially by heating quicklime and carbon
together in an electric furnace. Used for the generation of acetylene and
for making calcium cyanamide.
a. White powder or colorless crystals; CaCO3 . One of the most
stable, common, and widely dispersed of materials. It occurs in nature as
aragonite, calcite, chalk, limestone, lithographic stone, marble, marl,
and travertine. Referred to as whiting, it has many uses in ceramics to
introduce calcium oxide (CaO). Also used as a separator in glass firing.
CCD, 2; Lee; Kinney
b. Calcium carbonate (molecular weight, 100.09) crystallizes in two
crystal systems: hexagonal rhombohedral or hexagonal as calcite, and
orthorhombic as aragonite. Hexagonal calcium carbonate (calcite) is
colorless, white, yellowish, or rarely pale gray, red, green, blue, or
violet; sp gr, 2.710 (at 18 degrees C); Mohs hardness, 3; melting point,
1,339 degrees C (at 1,025 atm); decomposes at 898.6 degrees C; and soluble
in water, in acids, and in ammonium chloride solution. Orthorhombic
calcium carbonate (aragonite) is colorless, white, yellow, reddish,
bluish, or black; sp gr, 2.93, ranging from 2.85 to 2.94; Mohs hardness,
3.5 to 4.0; transforms to calcite at 520 degrees C; decomposes at 825
degrees C; and soluble in water, in acids, and in ammonium chloride
solution. Handbook of Chemistry and Physics, 2
c. Source of quicklime and of calcium metal.
A method used to consolidate floor dust in mine roadways in which calcium
chloride is applied with a wetting agent.
See:anorthite
See:margarite
Naturally abundant and widely exploited in industry. Main useful ores are
calcite, dolomite, anhydrite, and gypsum. Apatite is mined for phosphorus;
fluorite for fluorides; and colemanite and ulexite for boron.
Pryor, 3