Rocks and minerals Topic

Rocks and minerals

Science, Grade 4

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Study Guide Rocks and minerals Science, Grade 4

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ROCKS AND MINERALS What is in a Rock? Rocks are made up of many tiny pieces of minerals. Even if you smash a rock into a hundred pieces, ALL those would still be all the same mineral. Breaking it into pieces would not change the rock’s makeup. What are Minerals? Minerals are natural, nonliving crystals. They come in many sizes, shapes, and colors which is how scientists tell them apart. Minerals can be identified by their physical properties such as: color, luster, hardness, and streak color. Color is obvious, but what are luster, hardness, and streak color? • Luster refers to the way surface of mineral reflects light. • The hardness of a mineral refers to how easily it can be scratched. • Streak color is a physical property of minerals, which refers to the color streak a mineral leaves when scratched against a surface. Scientists use all these characteristics of minerals to identify them in nature. Lesson Checkpoint: What are rocks made of? Types of Rocks There are several types of rocks, and each is formed in a different way. Sedimentary Rocks How do sedimentary rocks form? Erosion is the process of bits of rocks, sand, soil, and dead matter being moved by the wind, water, and gravity. All the eroded materials that eventually settle on land or at the bottom of a body of water are known as sediment. As layers of sediment pile up, the top layers of sediment press the bottom layers together. The weight and pressure from the top layers cause the sediment on the bottom layers to harden, forming sedimentary rock. © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.

Igneous Rocks What are igneous rocks and how do they form? Igneous rocks form from molten rock called magma, which is the melted rock found beneath the Earth’s surface. Igneous rocks can form above and below the Earth. When magma reaches Earth’s surface and comes out of a mountain during a volcano, magma is then called lava. Once on the Earth’s surface lava will cool quickly forming igneous rocks. These type of igneous rocks do NOT form crystals (or if they do, they are tiny) because they cool too fast to do so. Forming crystals takes much longer. Crystals can form in igneous rock when magma slowly rises towards the surface of the Earth and then finds spaces to cool. After a long period of time the magma cools off and begins to harden. While the magma hardens, crystals form in the rocks. Metamorphic Rocks Metamorphic rocks are rocks that have changed due to heat and pressure. The weight of rocks pressing down on the other rocks causes the heat and pressure below the Earth’s surface. Metamorphic rocks can form from sedimentary, igneous, and other metamorphic rocks. Lesson Checkpoint: What are three types of rocks? © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.

The Rock Cycle The rock cycle is the recycling of old rocks into new rocks. It is an ongoing cycle. The rock cycle is caused by heat, pressure, chemical reactions, weathering, and erosion. During the rock cycle, all three type(s) of rocks can change from one type of rock to another. Rocks move through a cycle that takes millions of years. Lesson Checkpoint: What is the rock cycle? © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.