History of Igneous

	Revision 2 . . October 15, 2001 11:33 am by (logged).144.199.xxx [Stub no mo]
	Revision 1 . . October 13, 2001 11:42 pm by (logged).177.93.xxx

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Igneous rocks form when molten rock cools and solidifies (crystallizes).

Igneous rocks form when molten rock, called magma?, cools and solidifies. If the magma reaches the surface of the earth, it is called lava?. Igneous rocks are classified according to grain size as well as constituent mineralogy. Phaneritic? rocks contain minerals with grains (crystals) visible to the unaided eye. The individual mineral crystals are not visible in aphanitic? rocks.