CHAPTER 6LESSON 1

MINERALS AND ROCKS

PAGES 250-259

Minerals are natural, nonliving substances that make up rock. Rocks can be made up of more

than one mineral.

There are more than 3,000 kinds of minerals with different

properties. A property is a characteristic that describes

something.

The four properties of minerals are

color, hardness, luster, and

streak. You can identify

minerals by their properties.

COLORMinerals can be many different

colors or the same color.

HARDNESSHardness refers to a mineral’s

ability to scratch another mineral or be scratched by another mineral. Each mineral is

numbered one to ten.

Mohs’ Hardness Scale

LUSTERLuster refers to the way light bounces off the surface of a mineral. Minerals may be

metallic (shiny), dull, glossy, or pearly in luster.

STREAKA mineral’s streak is the color of the powder left behind when it is

scratched on a white tile.

The three main types of rocks are igneous, sedimentary, and

metamorphic.

Igneous rocks form from melted rock (magma or lava) cooling

and hardening.

When igneous rocks cool slowly,

large mineral grains form.

When they cool more quickly,

there is no time for large mineral grains to form. The rocks are more smooth.

Sedimentary rocks form from sediments that are pressed

together. Sediments are tiny pieces of rock, shells, or bits of

plants.

Sediments are deposited by wind and water (erosion) and over

time pile up on top of older layers of sediment. When they are

pressed or “cemented” together they form sedimentary rocks.

Fossils are often found in sedimentary rock. A fossil is a

trace of something that was once alive.

Metamorphic rocks are formed from igneous, sedimentary, or other metamorphic rock. The

high temperatures and pressures below the Earth’s surface can

change the properties of rocks, turning them into metamorphic

rocks.

Sedimentary, igneous, and metamorphic rocks can change from one type of rock to another

through the rock cycle.

The Rock Cycle