Weird But True Know-It-All: Rocks and Minerals

Weird But True Know-It-All: Rocks and Minerals — page 5
ROCKS what is a rock Let’s rock and roll Rocks make up every continent mountain and island on the planet But what is rock In simple terms a rock is a naturally occur ring solid object usually made from minerals Rocks are classified as one of three main types igneous sedimentary and metamorphic depending on how they’re formed A rock can also transform from one type to another over millions of years the processes of the rock cycle break it down or melt it change it and reform it into new rock MINERALS MATTER Within the three different categories of rocks what makes one rock different from another are the ways the different minerals combine together Rocks are usually made up of one or more minerals see page 100 to learn more about minerals Minerals are made up of tiny particles called atoms and these atoms are arranged in a particular particular pattern This pattern creates what are called crystals The crystals determine what a mineral looks like and they can shape how a rock looks too These crystals can affect whether a rock is rough or smooth and how hard it is Minerals also come in different different colors and that can affect a particular rock’s appearance too A mineral called hematite can make a rock red or brown It’s this mineral that gives sandstone sandstone its brown tint The mineral quartz gives rocks a range of colors though they usually tend to be light shades of gray Dacite usually bluish gray or pale gray is one rock that is often loaded with quartz 8