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 They occur naturally in the Earth’s crust.  They are inorganic.  They are solid.  They possess a definite chemical structure.  Rocks are simply aggregates of two or more minerals.  There exist roughly 4000 known minerals.  Most minerals are comprised of two or more elements.

 Atoms are the smallest particle that has all the characteristics of an element.  Atoms are made of subatomic particles.  Protons – found in nucleus, 1 AMU, (+)  Neutrons – found in nucleus, 1 AMU, neutral  Electrons – orbiting nucleus, 1/1836 AMU, (-)  Ions have gained or lost electrons  Isotopes carry varying number of neutrons.

 Crystal form – the external expression of the internal orderly arrangement of atoms.  Without space limitations, crystals are readily apparent. (example – Quartz)

 When space is limited, crystalline form is not readily apparent and takes on a different appearance. (example – Granite)

 Luster describes the appearance or quality of light reflected from the surface of a mineral.  Luster is described as metallic or non-metallic.  Metallic – (example Pyrite, eg: “Fool’s Gold”)

 Non-metallic minerals are described as:  Vitreous (glassy, example – Quartz, used in jewelry and time-keeping)  Pearly (example – Muskovite, used in jewelry, clothing accessories, and cosmetics)

 Silky (example – Calcite, used in cosmetics)  Resinous (example – Amber, used in jewelry)

 Earthy (dull, example – Chrysocolla, used in jewelry and cosmetics)

 Color is an unreliable way of classifying to the untrained eye. Some minerals may exhibit varying colors depending on concentration of elements. (example – Quartz)

 Streak is the color of a mineral in its powdered form. This indicator is much more reliable than “color”.  Streak is obtained by rubbing the mineral across a piece of hard, unglazed porcelain.

 Mineral hardness is measured on a Mohs scale.  The scale uses known and well-established standards of hardness and a comparison is drawn using the sample.

 Because some bonds in crystals are weaker than other bonds, minerals can be broken (cleaved) along planes formed by these weak bonds.  Not all minerals are prone to cleavage. Those that are break in such a way that they can be readily identified.

 Minerals can break in ways other than along planes caused by weak bonds.  These breaks are known as “fractures”.  These fractures can be curved (glass) or splintered (asbestos). Most fractures in minerals are irregular.

 Comparison between the density of a mineral to the density of fresh water.  If the density of a mineral is twice that of fresh water, the specific gravity of that mineral is 2.

 Of more than 4000 minerals identified, no more than a few dozen are considered abundant.  In fact, only 8 elements compose the bulk of these minerals and account for more than 98% (by weight) of the Earth’s crust. The minerals are called “rock- forming”.

 Silicates – comprised of combinations of Silicon and Oxygen atoms. This group is the most common mineral group.  Other than a few “pure” silicates (like quartz), silicates are electrically neutral.  Uses include lenses, gauges, adhesives, and many manufacturing processes.

 Carbonates – comprised of combinations of Carbon and Oxygen atoms.  These rock-forming minerals make up about ¼ of the Earth’s crust. But, they are economically important.  Calcite makes up the bulk of carbonates and is the basis for rocks like limestone and marble.  Halite (table salt) and Gypsum (used in wallboard) are two common carbonates.

 Reserves are identified deposits from which minerals can be profitably extracted.  Ores are useful metallic minerals that can be profitably extracted.  Non-metallic minerals used as building materials, abrasives, fertilizers, etc. are identified as industrial rocks and minerals.  Although these minerals occur naturally, they are typically not economically feasible as a resource unless they are refined (concentrated).

 Mining is used to extract minerals from the Earth’s crust.  Shaft, Slope, Drift, and Open-Pit mines have been used to obtain minerals.

 Bingham Canyon Copper Mine, near Salt Lake City, UT.  Over 2.5 miles across and almost 1 mile deep.

 Historically, machinery was on a “human scale”.

 Draglines are used to remove ore from the mine floor.

 Trucks used to move mined ore to surface.