71 Minerals, Rocks, and Soil-High

Minerals, Rocks, and Soil Written by Rachel Kamb

Introduction Earth provides everything you need to stay alive. It has water for drinking and air for breathing. It is home to plants and animals, which you need for so many reasons. But don't forget one more important thing Earth provides: land! The land is where you walk and where you play. Your home is built on land. But 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 differ a lot from one place to another. They come in many colors, shapes, and sizes, and can change quite a bit. They also help you in ways you may not realize.

Elements and Minerals To start thinking about what Earth is made of, let's start small... really small. Elements are what make up all matter, both living and nonliving. Everything on Earth is made from just over one hundred different elements. Carbon, helium, and zinc are a few of these elements. Do You Know? Elements are not the smallest parts of matter. The tiniest bits of each element are called atoms.

A mineral is a natural substance made of elements. Some minerals, including many kinds of metal, consist of just one kind of element. For example, silver is only made of silver, and iron is only made of iron. Many other minerals consist of two or more elements. For example, quartz is made of the elements silicon and oxygen. Earth has nearly 4,000 different minerals. Each one has its own mixture of elements. All minerals are solid, and they form in a pattern of crystals. Minerals have crystals because their atoms are arranged in tidy patterns. Different patterns make different crystal shapes. Minerals are also inorganic. This means they are not living, and they were never alive.

Rocks What happens when minerals combine? A rock is a hard, solid material found in nature. Most rocks are made of different minerals, just as a salad is made of different vegetables. If you pick up a rock, you might see several colors and patterns. These are usually 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 a rock in many ways. You can also compare one rock with another. Read the chart to learn some ways 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, depending 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.