Rocks: Mineral Mixtures

Section 1: Understanding Rock What exactly is rock? A solid mixture of crystals of one or more minerals, that range in all sizes from pebbles to formations that are thousands of kilometers long.

The Value of Rock Rock is an important natural resource. Used by early humans to make tools such as hammers, spears, knives, and scrapers. Used for centuries to make buildings, roads, and monuments. Certain types of rocks have helped build ancient and modern civilizations. Rock study has helped scientists to discover the history of life on Earth.

Machu Picchu, Peru 600 A.D. Ancient Civilization Rock Structure

Fossils Help provide information of life forms that lived thousands of years ago.

The Rock Cycle Rocks in the Earth’s crust are constantly changing shape and composition. The way the rock forms determines the type of rock that it is. The three main types of rocks are: igneous, sedimentary, and metamorphic.

Types of Rocks There are three main types of rocks: Igneous - formed when molten rock cools. Sedimentary – formed by the “cementing together” of small grains of sediment. Metamorphic – rocks changed by the effect of heat and pressure.

Igneous Rocks These are rocks formed by the cooling of molten rock (magma.) magma volcano Magma cools and solidifies forming igneous rocks

Sedimentary Rocks Sedimentary Rocks are rocks formed when particles of sediment build up and are “cemented together” by the effect of pressure and minerals. Getting older sea Fragments washed to the sea Sedimentary rocks Rocks are broken up by the action of weather

Metamorphic Rocks Metamorphic rocks are formed by the effect of heat and pressure on existing rocks. This can greatly affect the hardness, texture or layer patterns of the rocks. Magma Pressure from surface rocks metamorphic rock forming here heat

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