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20 Applicabons anc» !'vest.gations in Harth Science

IGNEOUS ROCK IDENTICATION KEY

		COMPOSTION			ORIGIN
		FELSIC	INTERMEDIATE	MAFIC
	Phaneritic (coursa-grainedj	Granrte	Dlotfte	Gabbro	lntftisive •magma}
* </i Ul te 3 H s	Aphanitic mne-grainsd) or Pcrphyritic	Rhyolite	Andesite .	Basalt	Exfrosivo (lavąi
	Glassy	Obsidian	asmummm 1 1 m S ES -		Exirusive (iava)
	Yasicular	Putnice		Scoria	Extrusive flava)

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Figurę 2.5 Hand samples that iliustrata ignsous ccmpositlons. Rocks with a glassy texture are coinposed of unordered atoms and often resomble inanufactured glass. This oxlrusive igneous rock consists of glassy fi bers and contains voids left by gas bubbies tha: escaped as lava solldified.

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