Properties of Minerals

What are the characteristics of a mineral? A mineral must be: Naturally occurring: Substance must be natural not man made, including construction materials made from minerals Inorganic: Substance can not come from materials that were once living Solid: Substance must have a definite volume and shape with tightly packed particles

What are the characteristics of a mineral? A mineral must have: Crystal Structure: The particles line up in a unique pattern that repeats over and over again The repeating pattern forms a crystal that has definite flat sides called faces that meet a sharp edges or corners Definite Chemical Composition: A mineral always contains the same elements in the same proportion These elements bond together to form compounds in which the element lose their identities

What are the characteristics of a mineral? Two groups of Minerals: Silicate Minerals: minerals that contain a combination of silicon and oxygen Nonsilicate Minerals: minerals that do not contain a combination of silicon and oxygen

How are minerals identified? Each mineral has its own specific properties that can be used to identify it. These properties include: Hardness/Mohs Hardness Test A mineral can scratch any other mineral that is softer than itself If a mineral is not on the scale, a mineral on the scale is used to scratch the unknown mineral Color Color can be used to identify only those few minerals that always have their own characteristic color

How are minerals identified? Streak: The streak of a mineral is the color of its powder The streak of a mineral can be observed by rubbing the mineral on a unglazed tile The color of a mineral may vary, but its streak does not Luster: Describes how a mineral reflects light from its surface Minerals that contain metal or a glassy finish have luster

How are minerals identified? Density: Each mineral has a characteristic density, meaning it does not change for that substance Crystal Shape: Minerals are classified into six groups depending on the number and angle of the crystal faces

How are minerals identified? Cleavage & Fracture: The way a mineral breaks apart can help to identify it Cleavage characterizes a mineral that breaks evenly Fracture describes a mineral that breaks in a unusual way Special Properties Magnetism Fluorescence Radioactive Electrical

How do minerals form? Evaporating Salt Water: when a body of salt water dries up, minerals such as gypsum and halite are left behind. Metamorphic Rocks: when changes in pressure, temperature or chemical makeup alter a rock. Minerals that form in this rock are: calcite, garnet, graphite, magnetite, and talc.

How do minerals form? Limestones: surface water and groundwater carry dissolved materials into lakes and seas, where they crystallize on the bottom. Hot-Water Solutions: groundwater works its way downward and is heated by magma, reacting with minerals to form a hot liquid solution. Mineral examples are gold, copper, pyrite, and galena.

How do we get Minerals? Ore: a mineral deposit large enough and pure enough to be mined for profit. Surface Mining: when mineral deposits are close to the surface for mining. Types of surface mines are open-pit, surface coal mines, and quarries. Subsurface mining: when mineral deposits are too deep within the Earth to be surface mined.

How do we get minerals? Responsible mining: mining can destroy or disturb the habitats of plants and animals. Waste products from a mine may get into water sources which pollutes surface water and groundwater. Reclamation: the process by which land used for mining is returned to its original state after the mining is completed.

How do we use minerals? Metallic Minerals: have shiny surfaces, do not let light pass through them, good conductors of heat and electricity. Examples include: gold, silver, and copper Nonmetallic Minerals: have shiny or dull surfaces, may let light pass through, good insulators of electricity. Most widely used minerals in industry. Examples include: calcite, bauxite, magnetite Gemstones: nonmetallic minerals; highly valued for their beauty and rarity rather than their usefulness. Examples include: diamond, ruby, sapphire, emerald, topaz.