IGNEOUS ROCK SPECIMEN

Rocks are simply defined as an aggregate of minerals. There three classifications Igneous Rocks formed  from cooled lava and magma associated with volcanic activity. Sedimentary Rocks formed from compacting sediments (pebbles, sand and clay) often below sea level. Metamorphic Rocks forms from preexisting rocks that get buried and remain in a solid state while immersed at various levels of heat and pressure.   

Igneous Rocks

It is essentially a silicate melt and may contain, as well as silicon and oxygen, other elements, particularly aluminum, iron, calcium, sodium, potassium and magnesium. These combine, as the magma or lava crystallizes, to form silicate minerals, which in combination make up igneous rocks.

Igneous Rocks: Phaneritic “visible crystals” from cooling magmas

White Granite

Gray Granite

Red Granite

Pink Granite

Diorite

Gabbro

Igneous Rocks: Porphyry from two “stage cooling” with phenocryst

White Granite Porphry

White Granite Porphyry

Diorite Porphyry

Rhyolite Porphyry

Rhyolite Porphyry

Rhyolite Porphyry (Rare Llanite)

Andesite Porphyry (Albite)

Andesite Porphyry (Hornblende)

Gabbro Porphyry

Igneous Rocks: Aphanitic “without visible crystals” from cooling lavas

Rhyolite

Rhyolite

Andesite

Basalt

Basalt

Basalt with Olivine Xenolith

Igneous Rocks: Vesicular from gaseous cooling

Pumice

Pumice

Scoria

Scoria

Vesicular Rhyolite 

Vesicular Rhyolite (with calcite) 

Vesicular Basalt

Vesicular Basalt

Vesicular Basalt

Igneous Rocks: Glassy from rapid cooling

Obsidian

“Snowflake” Obsidian

Red Obsidian

Igneous Rocks: Pyroclastic

Tuff Breccia

Tuff Conglomerate

Ignimbrite

Igneous Rocks: Pegmatites

Feldspar Pegmatite

Tourmaline Pegmatite

Feldspar Pegmatite

Igneous Rocks: Ultra Mafic origins

Dunite

Peridotite

Basalt with Serpentine veins

Data: Pellant, Chris. Smithsonian Handbooks. Rocks and Minerals: The clearest recognition guide available. A Dorling Kindersley Book.

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