What are minerals?How are minerals identified?

Pyrite or “Fool’s Gold”Gold

Minerals are …

Nonliving (inorganic), solid substances. They occur naturally 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.

Pyrite with its greenish-black streak.

Hematite with its reddish 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.

1 2 3 4 5 6 7 8 9 10

Talc Gypsum Calcite Fluorite Apatite Feldspar Quartz Topaz Corundum Diamond

Mohs’ Hardness Scale

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 CharacteristicsFluorescence

• 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