Petrology: Study of Rocks
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Questions and Answers

What characterizes igneous rocks with high amounts of silica?

  • They usually appear light in color. (correct)
  • They are typically dark in color.
  • They often have a fine-grained texture.
  • They are formed from magma that remains underground.

    • What defines intrusive igneous rocks?

  • They originate from magma that cools beneath the Earth's surface. (correct)
  • They are generally fine-grained and dark-colored.
  • They cool and crystallize at the Earth's surface.
  • They form from lava that erupts from volcanoes.

    • Which igneous rock is described as light-colored and composed mainly of quartz and feldspar?

  • Obsidian
  • Gabbro
  • Basalt
  • Granite (correct)

    • Which statement is TRUE regarding obsidian?

    <p>It is used for tool making by Native Americans.</p> Signup and view all the answers

    What is the main characteristic of basalt as an igneous rock?

    <p>It is a mafic rock that is dark-colored.</p> Signup and view all the answers

    How does pumice primarily differ from other igneous rocks?

    <p>It has abundant vesicles and is used for cleaning.</p> Signup and view all the answers

    What feature is typical of igneous rocks that indicates their formation?

    <p>The interlocking texture of the grains.</p> Signup and view all the answers

    Which igneous rock is commonly found in the deep oceanic crust?

    <p>Gabbro</p> Signup and view all the answers

    What is the primary factor that determines the texture of igneous rocks?

    <p>The size and shape of the crystals</p> Signup and view all the answers

    Which type of igneous rock is formed through rapid cooling of lava above ground?

    <p>Obsidian</p> Signup and view all the answers

    Which of the following best describes coarse-grained igneous rocks?

    <p>Formed below the surface with large crystals</p> Signup and view all the answers

    What is the meaning of the term 'extrusive' in relation to igneous rocks?

    <p>Formed as lava cools and solidifies above ground</p> Signup and view all the answers

    What classification of igneous rocks includes large crystals embedded in a groundmass of smaller crystals?

    <p>Porphyritic</p> Signup and view all the answers

    Which property distinguishes andesite from basalt?

    <p>Color and mineral composition</p> Signup and view all the answers

    Which igneous rock is known for being glassy and having no crystal formation due to rapid cooling?

    <p>Obsidian</p> Signup and view all the answers

    Which of the following statements about igneous rocks is true?

    <p>Igneous rocks can be classified based on their grain size and formation process.</p> Signup and view all the answers

    What type of metamorphic rock forms from limestone?

    <p>Marble</p> Signup and view all the answers

    Which of the following is considered a non-foliated metamorphic rock?

    <p>Marble</p> Signup and view all the answers

    What is the process called that transforms sedimentary rocks into metamorphic rocks?

    <p>Metamorphism</p> Signup and view all the answers

    Which rock is formed from sandstone through metamorphism?

    <p>Quartzite</p> Signup and view all the answers

    Anthracite is a type of metamorphic rock that is derived from which original raw material?

    <p>Coal</p> Signup and view all the answers

    What initiates the rock cycle?

    <p>Magma</p> Signup and view all the answers

    What is the key difference between extrusive and intrusive igneous rocks?

    <p>Location of formation</p> Signup and view all the answers

    What is the process called that breaks down igneous rocks into sediments?

    <p>Weathering</p> Signup and view all the answers

    What processes are involved in the formation of sedimentary rocks?

    <p>Erosion, compaction, deposition, and cementation</p> Signup and view all the answers

    Which type of sedimentary rock is formed from the accumulation of organic debris?

    <p>Organic sedimentary rocks</p> Signup and view all the answers

    Which sedimentary rock is known for containing large, rounded clasts that are greater than two mm in diameter?

    <p>Conglomerate</p> Signup and view all the answers

    How does compaction contribute to the formation of sedimentary rocks?

    <p>It squeezes layers over time, merging grains together.</p> Signup and view all the answers

    Which of the following is a characteristic of chemical sedimentary rocks?

    <p>They precipitate from dissolved materials in water.</p> Signup and view all the answers

    What is the main constituent of limestone?

    <p>Calcium carbonate</p> Signup and view all the answers

    Which type of sedimentary rock is derived from mechanical weathering?

    <p>Clastic sedimentary rocks</p> Signup and view all the answers

    What primarily distinguishes sandstone from other sedimentary rocks?

    <p>It consists mostly of sand-size grains of mineral, rock, or organic material.</p> Signup and view all the answers

    What is the primary characteristic of foliated metamorphic rocks?

    <p>They have a layered or banded appearance.</p> Signup and view all the answers

    What type of metamorphism occurs mainly due to contact with magma?

    <p>Contact metamorphism</p> Signup and view all the answers

    Which of the following rocks is formed from the metamorphism of sandstone?

    <p>Quartzite</p> Signup and view all the answers

    Which sedimentary rock is known as a valuable source of both petroleum and water?

    <p>Sandstone</p> Signup and view all the answers

    What is the original rock from which a metamorphic rock is formed called?

    <p>Protolith</p> Signup and view all the answers

    How is gneiss typically characterized in terms of its granules?

    <p>Contains a high percentage of quartz and feldspar.</p> Signup and view all the answers

    Which metamorphic rock is derived from shale?

    <p>Slate</p> Signup and view all the answers

    Which of the following statements about metamorphic rocks is incorrect?

    <p>Metamorphic rocks cannot be produced from sedimentary rocks.</p> Signup and view all the answers

    Study Notes

    Rocks Overview

    • Rocks are solid masses of the lithosphere, composed of one or more minerals and organic matter.
    • Petrology is the scientific study of rocks.
    • Varied rock properties include color (dark, light, reddish, gray, brown, yellow, black), texture (fine, rough), hardness, and glossiness.

    Classification of Rocks

    • Three main classifications: igneous, sedimentary, and metamorphic.

    Igneous Rocks

    • Originates from the Latin "ignis," meaning fire; formed through cooling and crystallization of molten rock (magma).
    • Types are categorized based on formation location:
      • Extrusive (above ground, cooled quickly): e.g., Basalt, Obsidian, Pumice.
      • Intrusive (beneath the ground, cooled slowly): e.g., Granite, Gabbro.
    • Texture depends on cooling rates:
      • Rapid cooling results in fine-grained rocks.
      • Slow cooling results in coarse-grained rocks.
    • Classified further into:
      • Fine-grained: very small crystals (e.g., rhyolite).
      • Coarse-grained: large crystals (e.g., granite).
      • Porphyritic: large crystals surrounded by smaller ones.
      • Glassy: no crystals, smooth surface (e.g., obsidian).
    • Mineral composition distinction:
      • Low Silicates: dark-colored rocks.
      • High Silicates: light-colored rocks.

    Sedimentary Rocks

    • Formed through erosion, deposition, compaction, and cementation of sediments.
    • Types of sedimentary rocks:
      • Clastic: composed of fragments of pre-existing rocks.
      • Chemical: formed from mineral precipitation.
      • Organic: derived from accumulated organic debris (may contain fossils).
    • Examples include Conglomerate (large fragments), Sandstone (sand-size grains), Shale (fine-grained), Limestone (calcium carbonate-rich).
    • Significant applications: energy resources (oil, gas), building materials, and historical geology insights.

    Metamorphic Rocks

    • Arises from the transformation of existing rocks (igneous or sedimentary) under high pressure and temperature.
    • Regional metamorphism affects large areas, while contact metamorphism occurs near magma.
    • Protolith refers to the original rock before changes.
    • Types include:
      • Foliated: layered appearance (e.g., Slate, Gneiss).
      • Non-foliated: lack of layering (e.g., Marble, Quartzite).

    The Rock Cycle

    • Begins with molten magma, which solidifies into igneous rock (extrusive or intrusive).
    • Weathering breaks down igneous rocks into sediments.
    • Sediments are transported and undergo sedimentation, compaction, and cementation.
    • Buried sediments transform into metamorphic rocks under heat and pressure.
    • Eventually, metamorphic rocks may melt back into magma, continuing the cycle.
    • This process has taken place for over 4 billion years, continuously reshaping the Earth.

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    Rocks PDF

    Description

    This quiz explores the fascinating world of rocks, focusing on their properties and classifications. Discover how color, texture, and appearance define different types of rocks and the study of their formations. Test your knowledge of petrology and the characteristics of the lithosphere.

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