Igneous Rocks

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Rock Noun

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[rok]

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Rock

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A naturally occurring solid mixture of one or more minerals, volcanic glass, organic matter, or other materials.

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Example: This diagram shows the rock cycle, where magma cools to form igneous rock, which can then be transformed into other rock types through various geological processes.

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Rock Cycle Noun

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[rok sy-kuhl]

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Rock Cycle

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A model illustrating the continuous processes that create, change, and recycle different types of rock over geological time.

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Example: This diagram shows the rock cycle, where magma cools to form igneous rock, which can then be weathered into sediments or transformed by heat and pressure.

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Igneous Rock Noun

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[ig-nee-uhs rok]

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Igneous Rock

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A type of rock that forms from the cooling and solidification of molten rock material, either magma or lava.

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Example: This image shows a piece of granite, a type of igneous rock. The visible, interlocking crystals of different minerals formed as magma cooled slowly underground.

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Magma Noun

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[mag-muh]

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Magma

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Molten rock material, containing dissolved gases and suspended crystals, that is found deep beneath the Earth's surface.

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Example: This cross-section shows magma, which is hot molten rock, collected in a large chamber deep beneath the Earth's surface.

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Lava Noun

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[lah-vuh]

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Lava

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Molten rock, or magma, that has erupted onto the Earth's surface from a volcano or fissure.

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Example: Lava is molten rock that erupts from a volcano and flows onto the Earth's surface, where it cools to form igneous rock.

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Texture Noun

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[teks-cher]

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Texture

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A property of igneous rock determined by the size and arrangement of its mineral crystals, which indicates its cooling history.

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Example: This image shows six different types of igneous rock textures, determined by the size, shape, and arrangement of their mineral crystals.

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Intrusive Igneous Rock Noun

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[in-troo-siv ig-nee-uhs rok]

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Intrusive Igneous Rock

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Rock formed when magma cools and solidifies slowly beneath the Earth's surface, resulting in large, coarse-grained mineral crystals.

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Example: This image compares intrusive rocks (e.g., granite) with large crystals to extrusive rocks (e.g., basalt) with smaller crystals, showing a key visual difference.

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Extrusive Igneous Rock Noun

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[ek-stroo-siv ig-nee-uhs rok]

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Extrusive Igneous Rock

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Rock formed when lava cools and solidifies quickly on or near the Earth's surface, resulting in small, fine-grained crystals.

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Example: This image compares extrusive igneous rocks, which have small crystals from cooling quickly on the surface, with intrusive rocks, which have large crystals.

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Volcanic Glass Noun

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[vol-kan-ik glas]

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Volcanic Glass

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A rock type that forms when lava cools so rapidly that mineral crystals do not have time to grow.

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Example: This image shows a piece of volcanic glass, an igneous rock that forms when lava cools too quickly for crystals to grow, resulting in a glassy texture.

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Silica Noun

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[sil-i-kuh]

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Silica

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A chemical compound of silicon and oxygen that is a key component of magma, influencing its viscosity and rock type.

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Example: This image shows rose quartz, a common form of the mineral silica (SiO2), which is a major component of many igneous rocks.