70 Minerals, Rocks, and Soil-Mid

Minerals, Rocks, and Soil Written by Rachel Kamb

Introduction Earth gives you everything you need to stay alive. It has water for drinking. It has air for breathing. It has plants and animals that you need for many reasons. Earth also has land! Land is where you walk and play. Your home is built on land, too. What is land made of? Why is it important? In this book, you will learn about nonliving Earth materials that make up the land. Nonliving Earth materials can be very different from one place to another. They come in many colors, shapes, and sizes. They change in many ways.

Elements and Minerals Let's look at what makes up Earth. We'll start really small, with elements. The elements below make up all living and nonliving things. Do You Know? Elements are not the smallest parts of matter. The tiniest bits of each element are called atoms.

A mineral is made of elements. Some minerals are made of only one element. For example, silver is just made of silver. Iron is only made of iron. Many other minerals are made of two or more elements. For example, quartz is made of silicon and oxygen. Earth has almost 4,000 different minerals. Each mineral has its own mix of elements. All minerals are solid. They form in a pattern of crystals Different patterns make different crystal shapes. Minerals are also inorganic—they were never alive.

Rocks A rock is a hard, solid material. It is found in nature. Most rocks are made of different minerals. Look at a rock. It might have many colors and patterns. These are the bits and pieces of different minerals. The mix of minerals in one kind of rock helps you tell it apart from other kinds of rocks.

You can describe and compare rocks in many ways. Look at the chart. It shows you how to describe and compare rocks. HOW TO DESCRIBE AND COMPARE ROCKS Mineral composition Rocks have a special mixture of one or more minerals. Size Rocks can be huge boulders or small pebbles. They can be as big as a mountain or as tiny as a speck of dust. Shape Rocks can be flat, round, square, or almost any other shape. Color Rocks come in every color you can imagine. Many rocks have more than one color. It depends on the colors of their minerals. Texture Some rocks feel very rough, while others are smooth. They can have tiny grains; large, smooth chunks; or long pointed crystals. Some rocks are full of airholes. Hardness The Mohs Scale of Hardness compares how hard each mineral is within a rock. Talc is rated a 1 (very soft), and diamonds are rated a 10 (very hard). Patterns Rocks may have streaks, waves, or straight lines. They may have dots everywhere or be built layer upon layer. Some rocks do not have a clear pattern. Location An important way to describe a rock is by where in nature it is found. A beach may have different rocks than a forest, desert, or volcano.