Igneous Rocks

Front 1

o Very coarse grain (phaneritic) intrusive
o Form during the final stage of a magma’s crystallization
o Similar to granite, with abundant quartz, feldspar and mica.

Back 1

Pegmetite

Hint 1

Front 2

o Coarse grain (Porphyritic), very dark, intrusive
o Ultramafic
o Usually contains olivine as their primary mineral, frequently with other mafic minerals such as pyroxenes and amphiboles

Back 2

Peridotite

Hint 2

Front 3

o Coarse grain (Porphyritic), intrusive, mafic
o Usually black or dark green in color
o composed mainly of plagioclase and augite (pyroxene).
o The most abundant rock in the deep oceanic crust.
o equivalent in composition to basalts

Back 3

Gabbro

Hint 3

Front 4

o coarse-grained, intrusive, intermediate (between gabbro and basalt)
o composed primarily of plagioclase feldspar, amphibole, and pyroxine minerals with small amounts of biotite mica
o Intrusive form of Andesite

Back 4

Diorite

Hint 4

Front 5

o Coarse grained, (Porphyritic) intrusive, felsic
o composed mainly of quartz and feldspar (minor amounts of mica, amphiboles and others)
o Intrusive form of Rhyolite
o Most abundant rock in continental crust

Back 5

Granite

Hint 5

Front 6

o Fine grain (aphanitic), dark, Mafic, Extrusive
o composed mainly of plagioclase and pyroxene
o Equivalent in composition to Gabbros
o Most of the basalt found produced in Oceanic divergent boundaries, Oceanic Hotspots, mantle plumes and hotspots beneath the continental crust.

Back 6

Basalt

Hint 6

Front 7

o Fine grain (aphanitic), Extrusive, Intermediate
o composed mainly of plagioclase with other minerals (hornblende, pyroxene and biotite)
o Extrusive form of Diorite

Back 7

Andesite

Hint 7

Front 8

o Fine grain (aphanitic), light colored, Extrusive, Felsic
o typically contains quartz and feldspar minerals
o Extrusive form of Granite

Back 8

Rhyolite

Hint 8

Front 9

o Vesicular, light, Extrusive
o Forms from rhyolitic magmas
o rhyolitic composition

Back 9

Pumice

Hint 9

Front 10

o Vesicular, Dark, Extrusive
o Forms from basaltic magmas
o Usually has a composition similar to basalt, but can also be similar to andesite.

Back 10

Scoria

Hint 10

Front 11

o Glassy, extrusive
o forms when molten rock material cools rapidly
o composition similar to rhyolite and granite.

Back 11

Obsidian

Hint 11

Front 12

o Pyroclastic, sand size, extrusive
o Forms from the products of an explosive volcanic eruption
o Many tuff deposits form from magma with a rhyolitic composition, but andesitic, basaltic and other types of magma might contribute to the tuff

Back 12

Tuff

Hint 12