Igneous Rocks

Igneous rocks are rocks which solidify from molten material (magma). Cooling of the magma can occur deep beneath the surface (plutonic), beneath the surface but at relatively shallow depths (hypabyssal) or on the surface (volcanic). Igneous rocks come in a variety of forms and colors. For example two samples of granite, while mineralogically similar, may look quite different, and yet they are both granites. The links below are an attempt to show the common types of both plutonic and volcanic igneous rocks and some of the varieties that are found. It is by no means a complete list of the types and varieties that are found in the world. Click on the rock name to view a sample of that rock type.

Atlas of Igneous Rocks
Rock Name / Image	Texture	Composition	Occurance	Images
Andesite: Hornblende Andesite	Porphyritic	Intermediate	Volcanic	Close-up1•
Anorthosite	Phaneritic	Mafic	Plutonic	Close-up2•
Aplite	Phaneritic	Felsic	Hypabyssal	Close-up3•
Basalt	Aphanitic	Mafic	Volcanic	Close-up4•
Basalt: Amygdaloidal Basalt	Porphyritic	Mafic	Volcanic	Close-up5•
Basalt: Olivine Basalt Porphyry	Porphyritic	Mafic	Volcanic	Close-up6•
Bostonite (Trachyte Porphyry)	Porphyritic	Intermediate	Volcanic	Close-up7•
Carbonatite: Siderite Carbonatite	Phaneritic	Ultramafic	Plutonic	Close-up8•
Dacite	Porphyritic	Intermediate	Volcanic	Close-up9•
Diabase	Phaneritic	Mafic	Hypabyssal	Close-up10•
Diabase porphyry	Porphyritic	Mafic	Hypabyssal	Close-up11•
Diorite	Phaneritic	Intermediate	Plutonic	Close-up11a•
Diorite: Quartz Diorite (Tonalite)	Phaneritic	Intermediate	Plutonic	Close-up12•
Gabbro: Hornblende Gabbro 1	Phaneritic	Mafic	Plutonic	Close-up13•
Gabbro: Hornblende Gabbro 2	Phaneritic	Mafic	Plutonic	Close-up14•
Gabbro: Olivine Gabbro	Phaneritic	Mafic	Plutonic	Close-up15•
Granite: Alkalic Granite	Phaneritic	Felsic	Plutonic	Close-up16•
Granite: Biotite Granite	Phaneritic	Felsic	Plutonic	Close-up17•
Granite: Biotite Hornblende Granite	Phaneritic	Felsic	Plutonic	Close-up18•
Granite: Muscovite-Biotite Granite	Phaneritic	Felsic	Plutonic	Close-up19•
Granodiorite	Phaneritic	Intermediate	Plutonic	Close-up20•
Harzburgite (Pyroxenite)	Phaneritic	Ultramafic	Plutonic	Close-up21•
Ijolite	Phaneritic	Mafic	Plutonic	Close-up22•
Kimberlite	Porphyritic	Ultramafic	Volcanic Hypabssal	Close-up23•
Lamprophyre	Phaneritic	Mafic	Hypabyssal	Close-up24•
Latite Porphyry	Porphyritic	Intermediate	Volcanic	Close-up25•
Monzonite	Phaneritic	Intermediate	Plutonic	Close-up26•
Monzonite: Quartz Monzonite Porphyry	Phaneritic	Intermediate	Plutonic	Close-up27•
Norite	Phaneritic	Mafic	Plutonic	Close-up28•
Obsidian	Glassy	Felsic	Volcanic	Close-up29•
Peridotite: Olivine Peridotite	Phaneritic	Ultramafic	Plutonic	Close-up30•
Phonolite	Porphyritic	Intermediate	Volcanic	Close-up31•
Pumice	Frothy	Felsic	Volcanic	Close-up32•
Pyroxenite (Harzburgite)	Phaneritic	Ultramafic	Plutonic	Close-up33•
Rhyolite	Porphyritic	Felsic	Volcanic	Close-up34•
Rhyolite Porphyry	Porphyritic	Felsic	Volcanic	Close-up35•
Rhyolite Tuff	Pyroclastic	Felsic	Volcanic	Close-up36•
Scoria	Scoreaceous	Mafic	Volcanic	Close-up37•
Syenite: Alkalic Syenite	Phaneritic	Intermediate	Plutonic	Close-up38•
Syenite: Hornblende Syenite	Phaneritic	Intermediate	Plutonic	Close-up39•
Syenite: Nepheline Syenite	Phaneritic	Mafic	Plutonic	Close-up40•
Syenite: Nepheline-Sodalite Syenite	Phaneritic	Mafic	Plutonic	Close-up41•
Tonalite (Quartz Diorite)	Phaneritic	Intermediate	Plutonic	Close-up42•
Trachyte Porphyry	Porphyritic	Intermediate	Volcanic	Close-up43•
Trachyte Porphyry (Bostonite)	Porphyritic	Intermediate	Volcanic	Close-up44•

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