NSSS4.1

toc =4.1 Properties of Minerals=

Vocabulary

 * Inorganic**: Inorganic means that the mineral is not from materials that were once a living thing.
 * Crystal**: Particles of a mineral that are in a repeating pattern and forms a solid is called a crystal.
 * Element**: A substance that is composed of a single kind of atom.
 * Compound**: A substance that is composed of two or more elements and are combined so that the elements no longer have distinct properties.
 * Mohs Hardness Scale**: A scale that ranks ten minerals from softest to hardest.
 * Streak**: The color of a minerals powder is called the streak.
 * Luster**: The term used to describe the amount of light the mineral reflects.
 * Cleavage**: The property of some minerals that break easily on flat surfaces.
 * Fracture**: A description of how a mineral looks when it breaks apart in an irregular way.
 * Fluorescence**: A property of some minerals that glow under ultraviolet light.

**Introduction**

 * If you have ever been to a museum, you might have seen a place called the " Hall of Minerals".
 * Over there, many minerals are displayed that you have never heard or seen.
 * One good example is " //sphalerite.// "
 * Sphalerite is a mineral that has a ruby red color.
 * It is also a source of zinc and gallium and these metals are used in products from" tin cans " to computer chips.

What Is a Mineral

 * A mineral is an inorganic solid that naturally occurs which has a definite chemical composition.
 * **Naturally Occurring**
 * Cement, bricks, steel and glass are not naturally occurring as they are made from substances found in the crust and then manufactured.
 * **Inorganic**
 * A mineral that is inorganic means that it is not from materials that were once parts of living things.
 * One example of an inorganic mineral is coal.
 * It is made from dead plants and animals.
 * **Solid**
 * Minerals are always solids as their particles are packed very tightly together so that they won't move like the particles in a liquid.
 * It is always has a definite volume and shape.
 * **Crystal Structure**
 * Crystals are particles of a mineral that are in a repeating pattern and form solids called crystals.
 * A crystal has flat sides ( which are technically called faces ) that meet at sharp edges called corners.
 * **Definite Chemical Composition**
 * A mineral always has a definite chemical composition as it always contains a certain amount of elements.
 * An element is a substance that is composed of a single kind of atom.
 * All the atoms of an element carry the same physical and chemical properties.
 * Almost all of the minerals that scientists have discovered are compounds.
 * A compound is a substance that is composed of two or more elements which are combined so that the elements no longer have distinct properties.
 * The elements of a compound are said to be chemically joined.
 * Each compound has its own properties that are usually different from the properties of elements that form it.
 * An example of a compound is cinnabar.
 * It is made from the elements mercury and sulfur.

Identifying Minerals
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 * Every mineral has its own specific properties which could be used to identify it.
 * Minerals are identified by hardness, color, streak, luster, density, crystal systems, cleavage and fractures and their special properties.
 * **Hardness**
 * To identify the minerals hardness, a scientist named Friedrich Mohs, who was Australian, invented the Mohs Hardness Scale.
 * The Mohs Hardness Scale is a scale that ranks ten minerals from softest to hardest.
 * The softest known mineral is //talc// and the hardest is //diamond//.
 * **Color**
 * The color of a mineral can be an easily observed physical property.
 * Some minerals have their own characteristic color.
 * One example of a mineral that always has the same color is //malachite.//
 * Its color is always green.
 * Another example is //azurite//.
 * Its color is always blue.
 * There are also many minerals that have a range of colors.
 * A good example would be quartz as it comes in all sorts of colors.
 * **Streak**
 * The streak of a mineral is basically the color of its powder.
 * You can observe streaks when you rub a mineral on an unglazed plate which is also called a streak plate.
 * **Luster**
 * A luster of a mineral is the term used to describe the amount of light the mineral reflects.
 * Minerals that contain metals have a shiny luster.
 * Other terms are bright, metallic, earthy, silky, waxy, and pearly.
 * **Density**
 * Each mineral has its own special density
 * When geologists measure density, they use a balance to determine the mass of the sample
 * Geologists also put the minerals in water to see how much water the mineral displaces.
 * The amount of displaced water is the volume of the mineral and dividing the volume of the mineral by its mass gives you the density of the mineral.
 * **Crystal Systems**
 * Each mineral has its own crystal system
 * For example, magnetite and halite have a cubic crystal system while sulfur has a orthorhombic crystal system
 * **Cleavage and Fracture**
 * Cleavage
 * A mineral which can split easily along flat surfaces has the property known as cleavage
 * Depending on the arrangement of atoms in a mineral, it will break easier in one direction than in another
 * Feldspar and mica are two minerals which have cleavage
 * Fracture
 * The way a mineral looks after an irregular break is its fracture
 * Fractured quartz has a shell-shaped fracture, pure metals such as copper and iron, have a hackly fracture and soft minerals like clay have an earthy fracture.
 * **Special Properties**
 * Some minerals have the property known as fluorescence which is the ability to grow under an ultra-violet light.
 * These are some examples.
 * Lodestone ( natural magnet )
 * Uraninite ( radioactive )
 * Quartz ( electric properties )