Igneous Rocks

Igneous Rocks

Rocks formed through the cooling and solidification of magma or lava.

Sedimentary Rocks

Rocks formed by the accumulation and compaction of mineral and organic particles.

Metamorphic Rocks

Rocks that have been transformed by heat, pressure, or chemically active fluids.

Decompression Melting

Melting that occurs when pressure drops on hot rock, leading to the formation of magma.

Partial Melting

The process by which only a portion of a solid melts to form magma.

Lava

Molten rock that erupts onto the Earth's surface.

Felsic

Describes igneous rocks that are rich in feldspar and silica.

Intermediate

Igneous rocks with a composition between felsic and mafic.

Mafic

Describes igneous rocks that are rich in magnesium and iron.

Assimilation

The process by which magma incorporates surrounding rock material.

Mixing

The blending of different magmas or magmatic materials.

Phaneritic

A texture of igneous rocks where crystals are large enough to be seen with the naked eye.

Aphanitic

A texture of igneous rocks where crystals are too small to be seen without a microscope.

Porphyritic

A texture characterized by large crystals (phenocrysts) embedded in a finer-grained matrix.

Phenocrysts

Large crystals found in a porphyritic igneous rock.

Matrix/Groundmass

The finer-grained material in which larger crystals are embedded.

Glassy Texture

A texture of igneous rocks where the rock appears shiny and glass-like due to rapid cooling.

Vesicular Texture

A texture of igneous rocks characterized by the presence of gas bubbles, creating a sponge-like structure.

Plutonic Rocks

Igneous rocks that form below the Earth's surface, also known as intrusive rocks.

Volcanic Rocks

➢ Basics of the rock cycle:

➢ How igneous rocks form:

➢ Magma vs. Lava:

➢ How rocks melt and why:

➢ Types of melting at different plate boundaries:

➢ How is water added to rocks to lower melting temperature?

➢ How can magma chemistry be changed to allow for various rock types from a single magma chamber?

➢ Bowen’s Reaction Series:

A concept that explains the order of crystallization of minerals from cooling magma.

➢ Xenoliths:

Fragments of rock that are enveloped in a larger rock mass, often seen in igneous rocks.

➢ Igneous textures and what they indicate:

➢ Plutonic vs. Volcanic Rocks:

➢ Batholiths, Sills, & Dikes:

Types of plutonic structures; batholiths are large masses, sills are sheet-like intrusions, and dikes cut across layers.

➢ Related igneous rocks (ex: Gabbro and Basalt):

Gabbro is a coarse-grained plutonic rock, while basalt is a fine-grained volcanic rock.