What is a mineral? What is a mineral? A mineral is a naturally occurring, inorganic solid that has a crystal structure and a definite chemical composition. What is a mineral?

Naturally occurring –occurs in nature Cement, brick, and steel all come from substances in Earth’s crust. However, since these are manufactured by people, they are not considered minerals.

Inorganic –nonliving A mineral cannot be made of materials that were once part of a living thing. Coal forms naturally in Earth’s crust, but since it is formed from the remains of plants and animals that lived millions of years ago, it is not considered a mineral.

Solid – A mineral is always a solid with a definite shape and volume. Ice is a mineral. Water is not a mineral.

Crystal structure- The particles of a mineral line up in a pattern that repeats over and over again.

Definite chemical composition – A mineral always contains certain elements in definite proportions. The formula for salt is NaCl. Each molecule of salt contains one atom of sodium and one atom of chlorine. The formula for quartz is SiO2. Each molecule of quartz contains one atom of silicon and two atoms of oxygen.

Most minerals are compounds. Compounds – a substance made up of two or more elements that have been chemically joined Each compound has its own properties, which usually differs greatly from the properties of the elements that form it. Sodium, a soft metal which fizzes violently when put into water, and chlorine, a poisonous gas, make sodium chloride (NaCl), otherwise known as common salt! Although these are not minerals, they are good examples of compounds.

Element – a substance composed of a single kind of atom Elements cannot be broken down into simpler substances by ordinary chemical means. All the atoms of the same element have the same chemical and physical properties. All minerals contain one or more elements.

a mineral that is composed of only one element Native element – a mineral that is composed of only one element Au Gold Cu Copper Ag Silver

These characteristics are used to identify minerals. Identifying Minerals These characteristics are used to identify minerals. Hardness Color Streak Luster Density Crystal System Cleavage and fracture Special properties

Hardness is a measure of the resistance of a mineral to being scratched. Mohs scale consists of ten minerals arranged from 10(hardest) to 1(softest). A mineral can scratch any mineral softer than itself., but will be scratched by any mineral that is harder.

Color is an easily observed physical property Color is an easily observed physical property. It is not the most useful, since many minerals can occur in a variety of colors. Azurite is always blue Malachite is always green.. Quartz can be many colors.

The streak of a mineral is the color of its powder. Even though the color of a mineral may vary, its streak does not. The streak color and the mineral color are often different. Pyrite may look gold, but it produces a greenish-brown streak. Hematite may look black, but leaves a reddish-brown streak.

Luster is the way the surface reflects light from its surface.

Density-the amount of matter in an object or mass per unit volume To calculate density: Measure the mass Measure the volume 3. Divide mass by volume (1ml=1 cubic cm) 4. Density is measured in grams per cubic centimeter. Measured in grams per cubic centimeter

Crystal structure The repeating pattern of a mineral’s particles forms a solid called a crystal.

Cleavage A mineral that splits along flat surfaces has cleavage.

Fracture Fracture describes how a mineral looks when it breaks apart in an irregular way.

Special properties Fluorescence Magnetism