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The Probert Encyclopaedia of Rocks & Minerals

BABINGTONITE

Babingtonite is a mineral occurring in triclinic crystals approaching pyroxene in angle, and of a greenish black colour. It is a silicate of iron, manganese, and lime.
Research Babingtonite

BALAS RUBY

Balas ruby is a variety of spinel ruby, of a pale rose red, or inclining to orange colour.
Research Balas Ruby

BARITE

Picture of Barite

Barite or baryte is major ore of barium. It has a high specific gravity for a light coloured mineral and is a common gangue mineral in hydrothermal veins or as a replacement mineral in veins of limestone and dolomite. It is associated with lead, silver and antimony sulphides. It has the formulae BaSO4 and a relative hardness of 3. It was the first mineral to be found to be luminescent when heated, and led to the discovery of the luminescence of minerals. It is used as an ore of barium, for refining sugar, in the paper industry and as a pigment.
Research Barite

BARRERITE

Barrerite is a mineral closely related to stellerite, but confirmed as a distinct species of mineral in 1975. Barrerite is a hydrated silicate of sodium, potassium, calcium and aluminium, and was previously erroneously known as sodium stellerite.
Research Barrerite

BARYTO-CALCITE

Picture of Baryto-Calcite

Baryto-calcite is a mineral of a white or grey colour, occurring massive or crystallized. It is a compound of the carbonates of barium and calcium.
Research Baryto-Calcite

BASAL CLEAVAGE

Basal cleavage refers to cleavage parallel to the base crystal plane of a mineral.
Research Basal Cleavage

BASALT

Picture of Basalt

Basalt is an igneous rock, consisting of augite and triclinic feldspar, with grains of magnetic or titanic iron, and also bottle-green particles of olivine frequently disseminated. It is usually of a greenish black colour, or of some dull brown shade, or black. It constitutes immense beds in some regions, and also occurs in veins or dikes cutting through other rocks. It has often a prismatic structure as at the Giant's Causeway, in Ireland, where the columns are as regular as if the work of art. It is a very tough and heavy rock, and is one of the best materials for macadamising roads.
Research Basalt

BASANITE

Basanite (Lydian stone, touchstone or black jasper) is a smooth, black siliceous mineral. It is employed to test the purity of gold, the amount of alloy being indicated by the colour left on the stone when rubbed by the metal.
Research Basanite

BASIC ROCK

Basic rock refers to an igneous rock with a low percentage of silica and a high percentage of pyroxene, hornblende, and labradorite.
Research Basic rock

BASIN

In geology the term basin describes an isolated or circumscribed formation, particularly where the strata dip inward, on all sides, toward a centre. The term is especially applied to coal formations which are called coal basins or coal fields.
Research Basin

BATH STONE

Bath stone (Bath-Olite, roe-stone) is a species of limestone once used for building and found in the Lower Oolite in Wiltshire and Somerset, England. It is easily wrought in the quarry, but hardens on exposure to the air. It was called 'Bath' stone because several of the quarries were near to the city of Bath.
Research Bath Stone

BAUXITE

Picture of Bauxite

Bauxite is a sedimentary rock group of various aluminium oxides, a principal ore of aluminium, found in France and Jamaica. Bauxite is often formed when aluminium-rich clays are carried away and deposited elsewhere. Bauxite was named after the place where it was first found, Les Baux in France. It has a relative hardness of 1 to 3.
Research Bauxite

BAYLDONITE

Picture of Bayldonite

Bayldonite is a secondary mineral formed in the oxidation zones of copper ore-bearing veins. It is usually found as a green or yellow coloured encrustation on the surface of other minerals and rocks. Bayldonite is named after the physician John Bayldon who first discovered it in a mine in Cornwall, England. Bayldonite was first classified as a mineral in 1865, but its chemical formulae was not discovered until 1956 when it was found to be Cu3Pb(AsO4)2(OH)2. Bayldonite forms as granular masses, as powdery habits, and as crusts on rock surfaces. It has a monoclinic crystalline structure with distinct crystals unusual.
Research Bayldonite

BED

In geology, the term bed describes a layer or seam, or a horizontal stratum of one formation between layers of others, for example a bed of coal, iron, etc.
Research Bed

BEDDING

Bedding refers to the arrangement of sedimentary rocks in about parallel layers or strata which correspond to the original sediments.
Research Bedding

BELONITE

Belonites are minute acicular or dendritic crystalline forms sometimes observed in glassy volcanic rocks.
Research Belonite

BEMBRIDGE BEDS

In geology the Bembridge Beds are a fossiliferous division of the Upper Eocene strata, principally developed at Bembridge in the Isle of Wight, consisting of marls and clays resting on a compact, pale-yellow or cream-coloured limestone, called Bembridge limestone. Their most distinctive feature is the mammalian remains of the Palaeotherium and Anoplotherium.
Research Bembridge Beds

BENITOITE

Picture of Benitoite

Benitoite is a mineral silicate of barium and titanium used as a gem stone. It occurs in a wide range of colours, commonly blue, but also purple, pink or white or colourless. Benitoite sometimes displays dichrorism - two colours occurring within a single crystal. It has a relative hardness of 6.
Research Benitoite

BERGMEAL

Bergmeal is an earthy substance, resembling fine flour. It is composed of the shells of infusoria, and in Lapland and Sweden was formerly sometimes eaten, mixed with flour or ground birch bark, in times of scarcity. This name is also given to a white powdery variety of calcite.
Research Bergmeal

BERTHIERITE

Picture of Berthierite

Berthierite, named after the French naturalist Berthier, is a double sulphide of antimony and iron, of a dark steel-grey colour.
Research Berthierite

BERYL

Picture of Beryl

Beryl (beryllium aluminium meta-silicate) has the formulae Be3Al2Si16O18 and a relative hardness of 8. It has a characteristic six-sided outline and is used as a gem stone of various colours, its green variety being emerald.

Beryl is also the major source of the rare element beryllium, a light metal similar to aluminium.
Beryl is quite common and occurs usually in granite rocks, mica schists and with tin ores.
Research Beryl

BINDHEIMITE

Bindheimite, named after Bindheim who analysed it, is an amorphous antimonate of lead, produced from the alteration of other ores, such as jamesonite.
Research Bindheimite

BIOTITE

Picture of Biotite

Biotite, named after the naturalist Biot, is a widely distributed rock forming mineral and occurs in igneous and metamorphic rocks and is a common member of the mica group. It has the formulae K(Mg,Fe) 2(Al,Fe)Si3O10(OH, F) 2 and a relative hardness of 3.
Research Biotite

BISILICATE

A bisilicate is a salt of metasilicic acid, so called because the ratio of the oxygen of the silica to the oxygen of the base is as two to one. The
bisilicates include many of the most common and important minerals.
Research Bisilicate

BISMUTH

Picture of Bismuth

Bismuth is a common metal element occurring in oxides, sulphides and carbonate compounds and also in its natural state. Bismuth has some unusual properties. It expands on freezing, and it exhibits diamagnetism - it pulls away from a magnet.
Research Bismuth

BISMUTHINITE

Picture of Bismuthinite

Bismuthinite has the formulae Bi2S3 and a relative hardness of 2. It is an ore of bismuth, and the main commercial source of bismuth and occurs in veins that show definite relations to igneous rocks.
Research Bismuthinite

BISMUTHYL

Bismuthyl or bismuthite is a hydrous carbonate of bismuth. It is an earthy mineral of a dull white or yellowish colour.
Research Bismuthyl

BITUMEN

Bitumen is a rock formed from the decomposed remains of living organisms and occurs in four types, the best known being asphalt - which is used for road surfaces and roofing, other types being albertite, elaterite and ozokerite. Bitumen burnss like pitch, with much smoke and flame. It consists of 84 to 88 of carbon and 12 to 16 of hydrogen, and is found in the earth, occurring principally in the secondary, tertiary, and alluvial formations. It is a very widely spread mineral, and is now largely employed in various ways. As the binding substance in mastics and cements it is used for making roofs, arches, walls, cellar-floors, etc, water-tight, for street and other pavements, and in some of its forms for fuel and for illuminating purposes. The bricks of which the walls of Babylon were built are said to have been cemented with bitumen, which gave them unusual solidity.
Research Bitumen

BITUMINOUS ROCKS

Bituminous rocks refers to rocks that contain tar, petroleum, or asphalt - that is bitumen.
Research Bituminous rocks

BLACK CHALK

Black Chalk is a soft variety of argillaceous slate, containing 10 to 15 per cent of carbon, and used for drawing.
Research Black Chalk

BLACKBAND

Blackband or black-band is an earthy carbonate of iron containing considerable carbonaceous matter and valuable as an iron ore. Blackband occurs in beds in the coal-measures, and contains 10 or 15 or even 30 per cent of coaly matter. Most of the Scotch iron was obtained from it.
Research Blackband

BLENDE

Blende is a zinc ore. It generally contains more than half its weight in zinc, a quarter sulphur and often a small amount of iron.
Research Blende

BLOEDITE

Bloedite is a hydrous sulphate of magnesium and sodium.
Research Bloedite

BLOODSTONE

Picture of Bloodstone

Bloodstone is a dark green variety of chalcedony sprinkled with red jasper, hence the name.
Research Bloodstone

BOG EARTH

Bog earth is a soil composed for the most part of silex and partially decomposed vegetable fibre.
Research Bog Earth

BOG ORE

Bog ore is a variety of brown iron ore, or limonite, found in boggy or swampy land.
Research Bog Ore

BOLE

Bole is an earthy mineral occurring in amorphous masses , and composed chiefly of silica with alumina, iron and occasionally magnesia. It is of a dull yellow, brownish, or red colour, has a greasy feel, and yields to the nail. In ancient times, under the name of Lemnian bole or earth, one variety of it had a place in the materia medica. At present the best known bole of commerce is a coarse pigment known as Berlin and English red.
Research Bole

BOLEITE

Picture of Boleite

Boleite is a rare and complex secondary mineral of the halide group, reddish or purple in colour and usually formed in cube-shaped crystals. Boleite was first discovered in Boleo, Mexico and named after the location. It was confirmed as a distinct mineral in 1891. Boleite contains atoms of lead, silver, copper, chlorine and hydroxyl molecules and three molecules of water of crystallisation.
Research Boleite

BOLOGNA STONE

Bologna stone is radiated barite, or barium sulphate, found in roundish masses composed of radiating fibres. It was first discovered near Bologna, and hence its name. It is phosphorescent when calcined (heated and powdered).
Research Bologna Stone

BOLTONITE

Boltonite is a granular mineral of a greyish or yellowish colour, found in Bolton, Massachusetts. It is a silicate of magnesium, belonging to the chrysolite family.
Research Boltonite

BONE-ASH

Bone-ash or bone-earth is the earthy or mineral residue of bones that have been calcined so as to destroy the animal matter and carbon. It is composed chiefly of phosphate of lime, and is used for making cupels in assaying, etc.
Research Bone-Ash

BORACITE

Picture of Boracite

Boracite is a mineral of a white or grey colour occurring massive and in isometric crystals. It has the formulae Mg3B7O13Cl and a relative hardness of 7. It occurs associated with beds of halite, anhydrite, and gypsum and is formed by the evaporation of bodies of salt water.
Research Boracite

BORATES

Borates refers to a group of minerals in which the borate radical (BO3) is an important constituent.
Research Borates

BORAX

Picture of Borax

Borax (sodium tetraborate) is the sodium salt of pyroboric acid. It has the formulae Na2B4O710H2O and a relative hardness of 3. It forms large transparent six-sided prisms which have an alkaline reaction, effloresce in air, and when heated swell-up and melt to a transparent glass. Borax is used in the manufacture of enamel-ware, glass, as an antiseptic and is a food preservative. It is also useful in brazing and silver soldering as it dissolves metallic oxides, thus cleaning the surfaces of the metals to be united.
Research Borax

BORNITE

Picture of Bornite

Bornite, named after the mineralogist Von Born, is a valuable ore of copper, containing copper, iron, and sulphur. Bornite has the formulae Cu5FeS4 and a relative hardness of 3. It is a widely occurring mineral found in basic rocks and metamorphic deposits.
Research Bornite

BOTRYOGEN

Picture of Botryogen

Botryogen is a hydrous sulphate of iron of a deep red colour. It often occurs in botryoidal form.
Research Botryogen

BOTRYOIDAL

Botryoidal refers to resembling a bunch of grapes. A mineral of this type appears to have a surface covered with spherical bulges.
Research Botryoidal

BOTRYOLITE

Botryolite is a variety of datolite, usually having a botryoidal structure.
Research Botryolite

BOULANGERITE

Picture of Boulangerite

Boulangerite, named after the French mineralogist Boulanger, is a bluish-grey coloured lead ore. It contains 55 percent lead. It has a relative hardness of 2.5.
Research Boulangerite

BOULDER

A boulder is a class of rock more than 256 mm in diameter.
Research Boulder

BOURNONITE

Picture of Bournonite

Bournonite, named after the mineralogist Count Bournon, is an ore of lead, copper, and antimony which often exhibits twinned crystals. It occurs in veins formed at moderate temperatures and has the formulae PbCuSbS3 and a relative hardness of 3.
Research Bournonite

BOVEY COAL

Bovey coal is a kind of mineral coal, or brown lignite, burning with a weak flame, and generally a disagreeable odour. It is found at Bovey Tracey, Devonshire, England.
Research Bovey Coal

BOWENITE

Bowenite, named after G.T. Bowen, who analysed it in 1822, is a hard, compact variety of serpentine found in Rhode Island. It is of a light green colour and resembles jade.
Research Bowenite

BRASH

In geology, brash are broken and angular fragments of rocks underlying alluvial deposits.
Research Brash

BRAUNITE

Picture of Braunite

Braunite, named after Braun, is a native oxide of manganese, of dark brownish black colour.
Research Braunite

BRECCIA

Picture of Breccia

Breccia is a rock consisting of angular fragments of any kind, united by a matrix. The shape of the components indicates that they have been produced by fracture, and have not been subjected to rounding by attrition. Fault breccia is often found between the two walls of a geological fault, and is due to the breaking down of the rocky walls when grinding on one another. Mineral veins are often formed in fissures, and are brecciated later by movement of the walls. Another kind of breccia is produced when hot molten lava enters a lake or a stream; it is suddenly cooled and solidified, being at the same time shattered by the clouds of steam that are formed. Braccias differ from conglomerates in the angular nature of their fragments, and in the method of their origin.
Research Breccia

BRIMSTONE

Brimstone is another name for sulphur, though properly, brimstone is roll sulphur. Sulphur is purified by distillation, the vapour being led into brick-work chambers. Part of the vapour liquefies, falls to the bottom, and can be run off and cast in cylindrical moulds, and when solid is known as brimstone.
Research Brimstone

BRISTOL DIAMOND

A Bristol diamond (also known as Bristol stone or rock crystal) is a brilliant crystal of colourless quartz found in St Vincent's rock at Clifton near Bristol.
Research Bristol Diamond

BROCHANTITE

Picture of Brochantite

Brochantite, named after the French mineralogist Brochant de Villiers, is a basic sulphate of copper, occurring in emerald-green crystals. Brochantite was first identified at a mine near Sverdlovsk in the Ural mountains of Russia, and confirmed as a distinct mineral in 1824. Brochantite is an ore of copper, but a minor one.
Research Brochantite

BROMLIFE

Bromlife or alstonite, named after Bromley Hill near Alston, is a carbonate of baryta and lime, intermediate between witherite and strontianite.
Research Bromlife

BROMYRITE

Bromyrite or bromargyrite is a rare silver bromide.
Research Bromyrite

BRONZITE

Picture of Bronzite

Bronzite is a pyroxene which is co called from its sub-metallic lustre resembling tarnished bronze. It is a silicate of magnesia and iron.
Research Bronzite

BROOKITE

Picture of Brookite

Brookite, named after the English mineralogist, H J Brooke, is a source of titanium but deposits are usually too small to be of commercial use. It has the formulae TiO2 and a relative hardness of 6.
Research Brookite

BROWN SPAR

Brown Spar is the name given to some crystalline varieties of dolomite tinged with peroxide of Iron
Research Brown Spar

BRUCITE

Picture of Brucite

Brucite, named after Named after Dr. Archibald Bruce of New York, is a mineral decomposition product of magnesium silicates, especially serpentine. It has the formulae Mg(OH)2 and a relative hardness of 3. It is found in Texas, where it is white with a grey, green or blue tinge and is used in sugar-refining, in medicine as an antacid and laxative and as a source of magnesium. Brucite has an incredibly high melting-point making it useful for lining kilns and furnaces.
Research Brucite

BRUSHITE

Brushite, named after the American mineralogist, George J Brush, is a white or grey crystalline mineral consisting of the acid phosphate of calcium.
Research Brushite

BUCHOLZITE

Bucholzite, named after the German chemist Bucholz is another name for sillimanite.
Research Bucholzite

BUHRSTONE

Buhrstone or burestone is a name given to certain siliceous or siliceo-calcareous stones, whose dressed surfaces present a burr or keen-cutting texture, whence they were much used for millstones. The most esteemed varieties were obtained from the upper fresh-water beds of the Paris basin, and from the Eocene strata of South America.
Research Buhrstone

BUSTAMITE

Picture of Bustamite

Bustamite is a reddish-brown coloured secondary mineral usually found in manganese-bearing ore bodies. It is closely related to, but is significantly different to rhodonite, bustamite being not quite so dense and also containing calcium.
Research Bustamite

BYSSOLITE

Picture of Byssolite

Byssolite is an olive-green fibrous variety of hornblende.
Research Byssolite

 
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