What are minerals?

How are minerals identified?

Pyrite or “Fool’s Gold” Gold

Minerals are …

Nonliving

(inorganic),

solid

substances. They occur

natural

ly and have a

repeating structure

(crystal structure due to internal arrangement of atoms).

How are minerals used?

• Aluminum can be used for packaging, transport, and building.

• Beryllium is used in gemstones and fluorescent lights.

• Copper is used in electric cables, wires, and switches.

• Feldspar is used in glass and ceramics.

• Calcite is used in toothpaste and construction.

• Iron is used in buildings, automobiles, and magnets.

• Titanium is used in airplanes.

• www.mii.org/commonminerals.php

How are minerals identified?

• Minerals can be identified by their properties. – Color – Streak – Hardness – Luster – Cleavage – Fracture

Color

• Minerals come in a rainbow of colors.

• Minerals can change color when exposed to air and rain for a long time.

• A mineral can have different colors. • Color alone cannot be used to identify a mineral.

Malachite

Streak

• Streak is the color of the powder left behind when a mineral is rubbed against a streak plate. A streak plate is a rough white tile.

Hematite with its reddish streak.

Pyrite with its greenish black streak.

Galena with its dark gray black streak.

Hardness

• Hardness is a mineral’s ability to scratch other materials or be scratched by other materials.

• Mohs’ hardness scale ranks minerals from 1 to 10 according to their hardness.

• Talc, the softest mineral, is 1.

• Diamond, the hardest mineral, is 10.

• A mineral can scratch another mineral if its hardness value is greater than or equal to the other mineral’s hardness.

Mohs’ Hardness Scale 1 Talc 2 Gypsum 3 Calcite 4 Fluorite 5 6 Apatite Feldspar 7 Quartz 8 9 10 Topaz Corundum Diamond

Luster

• Luster is the way a mineral’s surface reflects light. – Metallic luster (how light reflects off metals such as gold, silver, and copper) – Nonmetallic luster (described as glassy, silky, waxy, pearly, earthy, or resinous-like plastic) Tourmaline has a glassy luster.

Cleavage

• Cleavage is the way that some minerals break into pieces with smooth, flat, regular shapes.

• Quartz is one of Earth’s most common minerals. This crystal forms as a six-sided prism with pointed ends. The ends look like six-sided pyramids.

www.sdnhm.org/fieldguide/minerals/index.html

Fracture

• Fracture is the property of breaking unevenly or along a curved surface.

Copper has an uneven or irregular fracture.

Special Characteristics “The Acid Test”

You can test minerals by putting them in vinegar.

If it instantly reacts (fizzing or bubbling – releasing CO2 gas), it is probably a carbonate mineral like calcite.

Special Characteristics Fluorescence

• Some minerals will glow when placed under short-wave or long-wave ultraviolet rays.

• Franklin and Ogdenberg, NJ are famous for their fluorescent minerals.

Calcite (red) and willemite (green) Glowing under shortwave ultraviolet light.

Special Characteristics Magnetism

• Many iron minerals will produce an invisible magnetic force field.

• “Lodestone” was used by Vikings more than a thousand years ago as compasses.

Magnetite