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Identification of Rocks by Megascopic StudiesPrepared By: Engr. Waseem Niazi
Megascopic Study of Igneous Rocks
Megascopic Study of Sedimentary Rocks
Megascopic Study of Metamorphic Rocks
METAMORPHISMMetamorphism is the process of mineralogical and structural changes of rocks in their solid state in response to physical and chemical conditions which differ from the conditions prevailing during the formation of the rocks, however, the changes occurring within the domains of weathering and diagenesis are commonly excluded.
Identification of Metamorphic RocksFoliationGrain SizeHardnessUsual ColorOtherRock Typefoliatedfinevery softlightgreasy feelSoapstonefoliatedfinesoftdark"tink" when struckSlatefoliatedfinesoftdarkshiny; crinkly foliationPhyllitefoliatedcoarsehardmixed dark and lightcrushed and stretched fabric; deformed large crystalsMylonitefoliatedcoarsehardmixed dark and lightwrinkled foliation; often has large crystalsSchistfoliatedcoarsehardmixedbandedGneissfoliatedcoarsehardmixeddistorted "melted" layersMigmatitefoliatedcoarseharddarkmostly hornblendeAmphibolitenonfoliatedfinesoftgreenishshiny, mottled surfaceSerpentinitenonfoliatedfine or coarseharddarkdull and opaque colors, found near intrusionsHornfelsnonfoliatedcoarsehardred and greendense; garnet and pyroxeneEclogitenonfoliatedcoarsesoft lightcalcite or dolomite by the acid testMarblenonfoliatedcoarsehardlightquartz (no fizzing with acid)Quartzite
