李松青.docx

李松青.docx

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Howtodistinguishthreekindsofrocks?

Therockisanaggregateofminerals.WeputrockdividerockintothreecategoriesincludingSedimentaryrocks,magmaticrocksandmetamorphicrocks.Accordingtothecause,structureandcompositionofmineral,whichformtherocks.Sedimentaryrockisalsocalledtherockformationwater,solidmixturehasexperiencedweathering,transportation,depositionandconsolidation.Undertheactionsofexternalforcebeforebecomingrock.Magmaticrockisalsonamedtheigneousrock.itisformedofCondensateofmagmathatinvadesoreruptsfromearth'ssurface.MetamorphicrockisakindofrockthatcomefromthealterationofMagmaticrockandsedimentaryrock.Wecanfigureoutthethreekindsofrockfromthefollowingfoursteps:

1.mineralcomposition

Mineralsaremainlyprimarymineralofmagmaticrocks，andQuartz,feldspar,hornblende,blackmica,pyroxeneandolivineisverycommoninmagmaticrock.Inadditiontosomeoftheoriginalmineral（Quartz,feldspar,whitemica）,SecondarymineralsaccountforanumberincludingCalcite,dolomite,kaolinite.Glauconiteandsoon.However,Metamorphicrockbesideshastheoriginalrockmineralcompositionandtypicalmetamorphicmineralssuchassericiteandgarnet.

2.structureandcomposition

Magmaticrocksarefeaturedwithgranularcrystal,porphyriticstructure.Inclasticsedimentaryrocks,argillaceousandbioclastic,chemicalstructureareasitscharacteristics.while,Metamorphicrockofmainstructureincludingcrystalloblastic,palimpsest,crushed.

3.constructionofrocks

Magmaticrockhasfluxion,porosity,almondandblockconstruction.And,SedimentaryrockhasbeddingstructuremainlyandContainsfossilspartially.Thenmetamorphicrockisfamousfortheconstructionofschistosity,MIT,block.

4.theoccurrence

MagmaticrockismainlyIntheformofintrusivebodyandeffusiverockoccupyleast.While,sedimentaryrocksaremainlypresentregularlayer.

李松青

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