Calcite Mineral Britannica
Calcium | Definition, Properties, & Compounds | Britannica
Calcium does not occur naturally in the free state, but compounds of the element are widely distributed. One calcium compound, lime (calcium oxide, CaO) was extensively used by the ancients.The silvery, rather soft, lightweight metal itself was first isolated (1808) by Sir Humphry Davy after distilling mercury from an amalgam formed by electrolyzing a mixture of …
Aragonite group | mineralogy | Britannica
Other articles where aragonite group is discussed: mineral: Carbonates: type: calcite, aragonite, and dolomite. The copper carbonates azurite and malachite are the only notable hydrous varieties.
Calcite Mineral Data
Found in sedimentary, igneous, and metamorphic rocks. Common world wide. Link to MinDat Location Data. From the Latin, calx, meaning lime. Comments: Purple-colored druse of …
Iceland spar | mineral | Britannica
Iceland spar, a transparent calcite used for polariscope prisms. See
Mineral
Mineral - Hardness, Mohs Scale, Crystalline: Hardness (H) is the resistance of a mineral to scratching. It is a property by which minerals may be described relative to a standard scale of 10 minerals known as the Mohs scale …
Calcite
Calcite - Mineral, Crystals, Sedimentary Rocks: A large percentage of the calcite in rocks was deposited in sedimentary environments; consequently, calcite is a constituent of several diverse sediments, sedimentary rocks, and …
Dolomite | rock | Britannica
In sedimentary rock: Mineralogy. Though ancient limestones and dolomites are composed of calcite and dolomite, respectively, other calcite group minerals such as magnesite (MgCO 3), rhodochrosite (MnCO 3), and siderite (FeCO 3) …
Marble
The main mineral in marbles is calcite, and this mineral's variation in hardness, light transmission, and other properties in divers directions has many practical consequences in preparing some marbles. Calcite crystals are doubly refractive—they transmit light in two directions and more light in one direction; slabs prepared for uses in ...
Mohs hardness | Definition, Table, Examples, & Facts | Britannica
Mohs hardness, rough measure of the resistance of a smooth surface to scratching or abrasion, expressed in terms of a scale devised (1812) by the German mineralogist Friedrich Mohs. The Mohs hardness of a mineral is determined by observing whether its surface is scratched by a substance of known or defined hardness.. To give numerical values to this physical property, …
Garnet
Garnet - Mineral, Crystals, Rocks: The rock-forming garnets are most common in metamorphic rocks. A few occur in igneous rocks, especially granites and granitic pegmatites. Garnets derived from such rocks occur sporadically in clastic sediments and sedimentary rocks. Typical occurrences of the common rock-forming garnets are given in the Table. Garnets …
Stalagmite | mineral formation | Britannica
Other articles where stalagmite is discussed: stalactite and stalagmite: stalagmite, elongated forms of various minerals deposited from solution by slowly dripping water. A stalactite hangs like an icicle from the ceiling or sides of a cavern. A …
Marble | Definition, Types, Uses, & Facts | Britannica
marble, granular limestone or dolomite (i.e., rock composed of calcium-magnesium carbonate) that has been recrystallized under the influence of heat, pressure, and aqueous solutions. Commercially, it includes all …
Geode | Crystals, Formation & Structure | Britannica
geode, hollow mineral body found in limestones and some shales. The common form is a slightly flattened globe ranging in diameter from 2.5 to more than 30 cm (1 to 12 inches) and containing a chalcedony layer surrounding an inner lining of crystals. The hollow interior often is nearly filled with inward-projecting crystals, new layers growing on top of old.
Calcareous sinter | mineral | Britannica
Other articles where calcareous sinter is discussed: sinter: Calcareous sinter, sometimes called tufa, calcareous tufa, or calc-tufa, is a deposit of calcium carbonate, exemplified by travertine. So-called petrifying springs, not uncommon in limestone districts, yield calcareous waters that deposit a sintery incrustation on objects exposed to their action. The cavities in calcareous sinter…
Mineral | Types & Uses | Britannica
Since a mineral has a definite composition, it can be expressed by a specific chemical formula.Quartz (silicon dioxide), for instance, is rendered as SiO 2, because the elements silicon (Si) and oxygen (O) are its only constituents and they invariably appear in a 1:2 ratio. The chemical makeup of most minerals is not as well defined as that of quartz, which is a …
Chalk | Sedimentary, Limestone, Calcium Carbonate | Britannica
chalk, soft, fine-grained, easily pulverized, white-to-grayish variety of limestone.Chalk is composed of the shells of such minute marine organisms as foraminifera, coccoliths, and rhabdoliths. The purest varieties contain up to 99 percent calcium carbonate in the form of the mineral calcite.The sponge spicules, diatom and radiolarian tests (shells), detrital …
Mineral
Mineral - Classification, Properties, Types: Since the middle of the 19th century, minerals have been classified on the basis of their chemical composition. Under this scheme, they are divided into classes according to their dominant anion or anionic group (e.g., halides, oxides, and sulfides). Several reasons justify use of this criterion as the distinguishing factor at the …
Calcite
Calcite is the most abundant carbonate on Earth. It is one of the forms of calcium carbonate (CaCO 3) and its name derives from the Latin word for lime, calx, and the related German word calcit. It was named as a mineral by Gaius Plinius …
Aragonite | Carbonate, Calcium, Crystals | Britannica
aragonite, widespread mineral, the stable form of calcium carbonate (CaCO 3) at high pressures.It may be distinguished from calcite, the commoner form of calcium carbonate, by its greater hardness and specific gravity.Aragonite is always found in deposits formed at low temperatures near the surface of the Earth, as in caves as stalactites, in the oxidized zone of ore minerals …
Strontianite | Sulfate Mineral, Carbonate Mineral, Calcium Mineral …
strontianite, a strontium carbonate mineral (SrCO 3) that is the original and principal source of strontium.It occurs in white masses of radiating fibres, although pale green, yellow, or gray colours are also known. Strontianite forms soft, brittle crystals that are commonly associated with barite, celestine, and calcite in low-temperature veins. . Notable deposits exist in North Rhine ...
Calcite
Calcite TrigonalCaCO3Silicate minerals represent more than 90% of the Earth's crust, producing the common rock-forming minerals of many igneous, sedimentary, and metamorphic rocks. ... Modified after Encyclopædia Britannica, 1911. Calcite with rhombohedral habit complicated by oriented growth faces. Size: 5.6 x 5.4 x 3.8 cm. Wessels Mine ...
Igneous rock
Common alteration products are talc or serpentine formed at the expense of olivine, chlorites replacing pyroxene and amphiboles, iron oxides replacing any mafic mineral, clay minerals and epidote formed from the feldspars, and calcite that may be formed at the expense of any calcium-bearing mineral by interaction with a carbon dioxide (CO 2 ...
Siderite | Iron Carbonate, Carbonate Minerals, Sedimentary …
Siderite, iron carbonate (FeCO3), a widespread mineral that is an ore of iron. The mineral commonly occurs in thin beds with shales, clay, or coal seams (as sedimentary deposits) and in hydrothermal metallic veins (as gangue, or waste rock). Manganese (Mn), magnesium (Mg), and calcium generally
Mineral
Mineral - Crystal Structures, Chemical Compounds: The external morphology of a mineral is an expression of the fundamental internal architecture of a crystalline substance—i.e., its crystal structure. The crystal structure is …
Paramorph | mineral | Britannica
Other articles where paramorph is discussed: pseudomorph: …composition (these pseudomorphs are called paramorphs; e.g., aragonite becomes calcite, and brookite becomes rutile); by the loss of an ingredient from the original compound (e.g., cuprite loses oxygen to form copper); by the addition of an ingredient to the original compound (e.g., anhydrite adds water to form gypsum, …
Alstonite | Carbonate Mineral, Calcium Magnesium, Barium …
Alstonite, a barium and calcium carbonate mineral, CaBa(CO3)2, with minor amounts of strontium. It is colourless or light gray or pink in appearance and is also transparent or translucent. Its crystal structure is orthorhombic and is identical to that of aragonite, with barium and calcium in
Magnesite | Uses, Properties & Formation | Britannica
Magnesite, the mineral magnesium carbonate (MgCO3), a member of the calcite group of carbonate minerals that is a principal source of magnesium. The mineral has formed as an alteration product from magnesium-rich rocks or through the action of magnesium-containing solutions upon calcite. Notable
Sedimentary rock
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. ... Dolomite is produced by dolomitization, a diagenetic process in which the calcium carbonate minerals aragonite and calcite are recrystallized ...
Carbonate mineral | Types, Properties & Uses
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. ... The commonest varieties, …
Cave
Cave - Solution, Erosion, Formations: As previously noted, the largest and most common caves are those formed by dissolution of limestone or dolomite. Limestone is composed mostly of calcium carbonate in the form of the mineral calcite. Dolomite rock consists of calcium magnesium carbonate, the mineral dolomite. Both these carbonate minerals are somewhat …
Calcite
Calcite is calcium carbonate (CaCO 3) and belongs to trigonal (rhombohedral) crystal system. It occurs in a wide variety of crystal habits - rhombohedrons, scalenohedrons, …
Chemical weathering | geology | Britannica
Other articles where chemical weathering is discussed: mica: Origin and occurrence: It alters rather easily during chemical weathering and thus is rare in sediments and sedimentary rocks. One stage in the weathering of biotite has resulted in some confusion. During chemical weathering, biotite tends to lose its elasticity and become decolorized to silvery gray flakes. In …
Calcite Mineral | Uses and Properties
Calcite is a rock-forming mineral with a chemical formula of CaCO 3. It is extremely common and found throughout the world in sedimentary, metamorphic, and igneous rocks. Some geologists consider it to be a "ubiquitous mineral" - …
Calcite | Mineral, Rock & Crystal | Britannica
calcite, the most common form of natural calcium carbonate (CaCO3), a widely distributed mineral known for the beautiful development and great variety of its crystals. It is polymorphous (same chemical formula but different crystal structure) with the minerals aragonite and vaterite and with …
Limestone | Characteristics, Formation, Texture, Uses, & Facts | Britannica
Limestone, sedimentary rock composed mainly of calcium carbonate, usually in the form of calcite or aragonite. It may contain considerable amounts of magnesium carbonate (dolomite) as well; minor constituents also commonly present include clay, iron carbonate, feldspar, pyrite, and quartz.
Cementation | Diagenesis, Lithification & Compaction | Britannica
cementation, in geology, hardening and welding of clastic sediments (those formed from preexisting rock fragments) by the precipitation of mineral matter in the pore spaces. It is the last stage in the formation of a sedimentary rock.The cement forms an integral and important part of the rock, and its precipitation affects the porosity and permeability of the rock.
marble summary | Britannica
The main mineral in marble is calcite. Commercially, "marble" includes all decorative calcium-rich rocks that can be polished, as well as some serpentines. Marbles are used principally for buildings and monuments, interior decoration, statuary, tabletops, and novelties. Colour and appearance are their most important qualities.