Chapter 6 Lesson 1 Minerals and Rocks Pages 250-259

Minerals are natural, nonliving substances that make up rock 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 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.

Minerals can be many different colors or the same color.

HARDNESS Hardness 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

LUSTER Luster refers to the way light bounces off the surface of a mineral. Minerals may be metallic (shiny), dull, glossy, or pearly in luster.

STREAK A 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 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 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 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