chapter 3 minerals

Inorganic

a mineral must also be this. It is something NOT formed from living things or the remains of living things. Coal forms in the earth's crust but is not inorganic because it comes from the remains of plants.

cleavage

a mineral's ability to split easily along flat surfaces.

solution

a mixture in which one substance is disolved in an other.

vein

a narrow deposit of a mineral that is sharply different from the surrounding rock.

color

the color of a mineral is an easily observed physical property. Color alone often provides too little information to make identification.

magma

the molten mixture of rock-forming substances, gases and water from mantle.

crystal structure

the particles of a mineral line up in a pattern that repeats over and over again. The mineral's repeating pattern form a solid called a crystal.

crystallization

the process by which atoms are arranged to form a material with a crystal structure.

gemstone

a hard, colorful mineral that has a brilliant or glossy luster and is valued for its appearance.

geode

a hollow rock inside which mineral cyrstals have formed.

halite

a mineral formed through the evaporation of a solution. Example is table salt.

Definite chemical composition

a mineral has a definite chemical composition or range of compositions. this means that a mineral always contains certain elements in definite proportions. Almost all minerals are compounds that have its own properties, or characteristics, which usually differ greatly from the properties of the elements that form it.

mineral

a naturally occurring, inorganic solid that has a crystal structure and a definite chemical composition. A substance must have all 5 characteristics to be a mineral.

crystal

a solid in which the atoms are arranged in a pattern that repeats again and again. A crystal has flat sides, called faces, that meet at sharp edges and camers.

alloy

a solid mixture of two or more elements; at least one of which is a metal. Minerals from which metals can be removed in usable amounts are called this. Steel is an example of this.

The properties of identifying minerals are

color, streak, luster, density, hardness, crystal systems, cleavage & fracture, and special properties.

identifying minerals

geologists have identified about 3800 minerals. Each mineral has characteristic properties that can be used to identify it. Learning the properties of minerals allows you to be able to identify many common minerals around you.

quartz

has a glassy luster.

The mineral azurite

is always blue. No other mineral looks like this.

The mineral malachite

is always green. No other mineral looks like this.

Galena

is an ore of lead that has a metallic luster. It is 3 times as heavy as quartz and its density is greater.

density

is the mass in a given space or mass per unit volume. Each mineral has a characteristic density. Density of a mineral always remains the same no matter what size. Density is found by dividing the mineral's mass by its volume. Density equals mass over volume.

lava

liquid magma that reaches the surface; also, the rock formed when liquid lava hardens.

ore

rock that contains a metal or economically useful mineral that can be mined and sold for profit

smelting

the process by which ore is melted to separate the useful metal from other elements.

fracture

the way a mineral looks when it breaks apart in an irregular way.

naturlly occuring

this means the substance must be formed by processes that occur in the natural world. The mineral quartz forms naturally as magma cools and hardens deep beneath Earth's surface. Man-made materials are not minerals, such as plastic, brick, glass and steel.

Solid

A mineral is always a solid, with definate volume and shape. The particles in a solid are packed tightly and cannot move like a liquid or gas.

streak

A streak test can give clues to a mineral's identity. Streak is the color of a mineral's powder. You can observe streak by rubbing a mineral against a piece of unglazed porcelain tile. Color may vary, but streak does not. Streak color and the mineral color ae often different.

luster

Another simple test to identify a mineral is to check this. The way a mineral reflects light from its surface is this. Minerals containing metals are often shiny. Other terms used to describe luster include earthy, wavy, and pearly.

Mohs hardness scale

One of the best ways to identify a mineral is a minerals hardness. Mohs harness scale ranks ten minerals from softest to hardest. Friedrich Mohs, an Austrian mineral expert invented this test. Hardness can be determined by a scratch test. Geologists determine a mineral's hardness by comparing itto the hardness of the minerals on the Mohs scale. Talc, number 1, is the softest and diamond, number 10 is the hardest.

metals

Some elements occur in nature in a pure form, and not as part of a compound. Almost all elements that form in nature in pure form are metals. Some examples are copper, silver, and gold.