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Eclogite is a rock which consists of pale-green augite, pale-green hornblende, pink garnet with sometimes also quartz, feldspar, cyanite, bronzite, iron ores and rutile. Such rocks occur in regions of xrystalline schists, as the Alps, and are believed to be of intrusive origin in some cases.
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In mineralology, efflorescence is the property which certain crystals possess of losing their clear transparent character and producing a light powder on the surface, eg washing-soda. Efflorescence is also the name given to the fine crystalline deposits (magnesium and sodium sulphates) which appear on walls, etc.
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Elaterite (also lnown as elastic bitumen or mineral caoutchouc) is a natural bitumen, soft, brown and elastic found in the lead mines of Castleton in Derbyshire and in Edinburgh.
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Emerald is a green precious stone variety of the mineral beryl. While pure beryl is colourless, the green of the emerald comes from various impurities in the stone. Brazilian emeralds usually contain calcite or pyrite, South African and Russian emeralds usually contain mica.
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Emery is an impure fine-grained form of corundum (aluminium oxide) of blackish or bluish-grey colour, chiefly found in shapeless masses and mixed with other minerals.in conjunction with iron oxides and spinel. Emery is very hard; is infusible, and is not attacked by acids; has the formulae Al2O3 employed widely as an abrasive: it is employed in cutting and polishing precious stones; in smoothing the surface of the finer kinds of lenses preparatory to their being polished; in the polishing of marble; by cutlers, locksmiths, glaziers, and other artisans. For all these purposes it is pulverized in large iron mortars or in steel mills, and the powder, which is rough and sharp, is carefully washed and sifted into eight or ten different degrees of fineness. Emery-paper and emery-cloth are made by laying a thin coat of glue upon the fabric, and dusting the emery from a sieve of the required size. Typically emery consists of 60 percent corundum and 40 percent iron oxide in the form of magnetite.
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Enargite is a relatively rare mineral found in vein and replacement deposits associated with pyrite, sphalerite, bornite, galena, chalcocite. It is used as an ore of copper. It has the formulae Cu3AsS4 and a relative hardness of 4.
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Enstatite is a common and widespread mineral with a relative hardness of six. It is found in mafic plutonic and volcanic rocks and often in both metallic and stony meteorites. It is a silicate of magnesium and iron and has the formulae Mg2Si2O6. Enstatite has various uses depending upon the quality of its crystals, and is used as a gemstone and for lining ovens, due to its very high melting point.
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The Eocene System is the oldest of the four geological systems into which the Tertiary era is divided.
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Epidote is a common mineral found in regional and metamorphic rocks of mafic composition and as a product of alteration of other minerals. It is sometimes used as a gemstone. It has the formulae Ca2(Al,Fe)3Si3O12(OH) and a relative hardness of 7.
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Epsomite (popularly known as 'Epsom Salts') is a mineral named after Epsom in Surrey, England where it is found occurring around mineral springs. Although large crystals of epsomite have been found, it is most commonly found as an encrustation or massive aggregate on the surface of other rocks and minerals as a white fibrous mass of acicular micro-crystals.
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In geology, erratics, or erratic blocks, ARE boulders or large masses of angular rock which have been transported to a distance from their original mountains by the action of ice during the glacial period. Thus on the slopes of the Jura Mountains immense blocks of granite are found which have travelled almost 100 km from their original situation. Similarly masses of Scotch and Lake-district granites and of Welsh rocks (some of which weigh several tons) occur not uncommonly in the surface soil of the Midland counties of England.
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In geology, eruptive rocks are those which, like lava, basalt, granite, etc, have broken through other rocks while in a molten state.
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Erythrite is a secondary mineral which often shows a vivid colour and occurs in thin crusts. It is an important indicator of cobalt mineral deposits, being formed through the oxidation of cobaltite in veins and has the formulae Co3(AsO4)2ù8H2O and a relative hardness of 3.
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Escar or eskar is a late geological formation in the superficial drift, generally consisting of a long linear ridge of sand and gravel, including pieces of considerable size. The materials are derived from the waste of till or boulder-clay, and their arrangement took place probably under water over which icebergs floated, for in Sweden particularly angular, erratic blocks are often deposited on the escar. They are called in Scotland Kaims or Kames.
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Ettringite is a mineral first found at Ettringen in Germany, and named after the place of its discovery. It is a hydrous sulphate of calcium and aluminium which forms small but beautifully formed hexagonal prism crystals, generally yellow in colour.
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Euclase is a variety of beryl and has the formulae BeAlSiO4(OH) and a relative hardness of 8.
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Eudialyte is a rare and complex silicate mineral easily soluble in acids.
Eudialyte crystals are trigonal and appear in prismatic or table-top shapes, often pink in colour they may also be yellowish-brown. Eudialyte was confirmed as a distinct mineral in 1819, but its chemical formula is still in doubt.
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Eurite is an acid, igneous rock of the granite group, which consists of quartz and feldspar with muscovite or garnet as accessory minerals, and is mostly found as dykes and veins traversing granite and crystalline schists.
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In geology, extravasation describes the issue of lava and other volcanic products from the earth.
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Abbreviations
Rocks & Minerals
