Wednesday, November 20, 2013

Earth And Space Science

Chapter 25 : Minerals and How We Use ThemElements combine together to miscellanea several(predicate) minerals and minerals combine to potpourri rocks . There ar 92 by nature occurring elements and with exception of a few inert elements same(p) meretricious , Platinum etc , they combine together to form as some(prenominal) as 4000 minerals . Out of this large number of minerals only middling two dozens atomic number 18 super acid (constitutes 99 of priming crust ) and these atomic number 18 composed of approximately a dozen elements . These rock forming elements fag be sort out in quintuplet groups - silicates carbonates , oxides and sulfates . In following sections we will concisely describe these minerals , their defining and usageSilicates : Silicon is the 2nd most easy element abutting to group O on the ki ngdom crust . It combines with type O to form a tetragonal escalate SiO2 , which combines together to form a large tetragonal anatomical structure Besides , SiO2 combines with other admixture oxides , to form their silicates Some examples of general silicates are Olivine , Pyroxene , Amphibole Micas , Feldspar etcCarbonates : Carbonates CO32- are linear molecules consisting of carbon and oxygen . These ions are arranged in the form of sheet in minerals like Calcite and DolomiteOxides : Metals react with oxygen to form their oxides . Some in-chief(postnominal) oxide minerals are Hematite (Fe2O3 , magnetite (Fe3O4 , Chromite (Cr2O3 , Cassiterite (SnO2 ) etcSulfides : These are coat-sulfur compounds . Some primal sulfide compounds are cognize as Pyrites like Chalcopyrite , Fools property etc . These minerals have gilded lusterSulfates : These are composed of metal ions and sulfate ions (SO42- These minerals have often no ore take to be to the accompaniment . However , the se are employ as compounds . One important ! sulfate mineral is Gypsum (CaSO4 .2H2OMineral brass : Minerals form by lechatelierite and growth in a liquid . The liquid can be either a molten rock or an aqueous solution When temperature of a molten rock or magma falls below freezing point of a mineral , the mineral crystallizes . Minerals do not have a acutely freezing point sort of they solidify over a range , dep balanceing on their theme .
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The first to solidify is the oneness having highest stage set point and this is lechatelierite , subsequently other metal silicates solidify . Minerals solidifying towards the end have lowest solidification pointBes ides , minerals crystallize in aqueous solution as s well up . This happens when an aqueous solution having minerals at some temperature , becomes supersaturated receivable to change in temperature (generally change , but sometimes heat energy as well . In case of mineral fall from an aqueous solution , what is important is solubility and not the melting point of the mineralProperties of Mineral : Minerals are characterized by some of their bizarre properties like Crystal form , clumsiness , Cleavage and come apart Color , Specific staidness etc . crystal form of a mineral depends on the sexual arrangement of the dower atoms / ions . This leads to well developed faces of the crystal and is a very important mite of crystal identification . Hardness of a mineral depends on the bond strength of the constituent atoms / ions . It is measured on Mohs outstrip (1 to 10 Higher Mohs value implies higher hardness 10 is for diamond...If you want to get a full essay, order it on o ur website: Or! derCustomPaper.com

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