Questions and Answers
What type of rock is formed when molten rock cools slowly and solidifies inside Earth's crust?
Which type of igneous rock is produced when molten rock cools quickly on Earth's surface?
What characterizes basaltic rock?
It is dark colored, has lower silica contents, and is rich in iron and magnesium.
What is a granitic rock?
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What does the term 'texture' refer to in igneous rocks?
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What is porphyritic texture?
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What does vesicular texture indicate?
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What is pegmatite?
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What type of rock can contain diamonds?
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The classification of igneous rocks is based on _____ and _____.
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The rate of cooling determines _____ in igneous rocks.
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Ores often occur in _____ such as pegmatites.
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Diamonds occur in _____.
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Why are some igneous rocks used as building materials?
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Study Notes
Classification of Igneous Rocks
- Igneous rocks are categorized as intrusive or extrusive based on their formation process.
- Intrusive rocks cool slowly beneath the Earth's surface, resulting in coarse grains.
- Extrusive rocks cool rapidly on the surface, leading to fine-grained textures.
Types of Igneous Rocks
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Basaltic Rock:
- Dark-colored with lower silica content, rich in iron and magnesium.
- Primarily composed of plagioclase and pyroxene minerals.
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Granitic Rock:
- Light in color with high silica content.
- Contains minerals such as quartz and potassium feldspar.
Rock Textures
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Texture Definition:
- Refers to the size, shape, and distribution of crystals or grains within the rock.
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Porphyritic Texture:
- Characterized by large, well-formed crystals embedded in a matrix of finer-grained crystals.
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Vesicular Texture:
- A spongy appearance resulting from trapped gas bubbles in lava during cooling.
Special Rock Types
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Pegmatite:
- Composed of very large-grained minerals; often contains rare ores like lithium and beryllium.
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Kimberlite:
- Rare ultramafic rock that can contain diamonds, formed under extreme pressure conditions.
Factors Influencing Rock Properties
- The classification of igneous rocks is based on the rate of cooling, mineral composition, and texture.
- Crystal size is directly influenced by the rate of cooling, with slower cooling allowing larger crystals to form.
- Ores frequently occur within pegmatites, while diamonds are typically found in kimberlites.
Uses and Applications
- Certain igneous rocks are valued as building materials due to their strength, durability, and aesthetic qualities.
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Description
Test your knowledge of igneous rocks in Earth Science Chapter 5. This quiz covers key terms like intrusive and extrusive rocks, helping you distinguish between their formation processes and characteristics. Perfect for reviewing the classification of these important geological structures!
