Minerals

What is a Mineral? All Minerals Must Meet the Following Criteria Naturally Occurring Naturally Occurring Inorganic Inorganic Solid at room temperature Solid at room temperature Definite Chemical Formula Definite Chemical Formula Definite Crystal Structure Definite Crystal Structure There are over 2000 minerals known and some are very rare—and yet 90% contain silicon and oxygen (SiO2)—the study of mineralogy is observing physical properties by performing simple tests.

Naturally Occurring Formed by natural processes not in the laboratory Formed by natural processes not in the laboratory - Is an Ice Cube a mineral? - Is an Ice Cube a mineral? - Is the ice on the windshield of a car a - Is the ice on the windshield of a car a mineral? mineral?

Inorganic Formed by inorganic processes; not living Formed by inorganic processes; not living Does not contain chains of carbon atoms Does not contain chains of carbon atoms

Definite Crystal Structure Highly ordered atomic arrangement of atoms in regular geometric patterns Highly ordered atomic arrangement of atoms in regular geometric patterns 8 ApatiteFeldsparDiamondQuartz

Definite Chemical Formula Minerals are expressed by a specific chemical formula Minerals are expressed by a specific chemical formula -Gold (Au) -Calcite (CaCO 3 ) -Quartz (SiO 2 ) -Pyrite (FeS 2 )

Composition of the Earth’s Crust  Eight Elements that make up over 98% of Earth’s Crust -Oxygen (O) -Silicon (SI) -Aluminum (Al) -Iron (Fe) -Calcium (Ca) -Sodium (Na) -Potassium (K) -Magnesium (Mg)

Where Do Minerals Come From? Magma Evaporation

How Are Minerals Identified? Color Color Luster Luster Hardness Hardness Streak Streak Density Density Crystal Shape Crystal Shape Cleavage and Fracture Cleavage and Fracture Special Properties Special Properties

Color Usually the first and most easily observed but least reliable Usually the first and most easily observed but least reliable -Some minerals are always the same color -Some minerals can have many colors QUARTZROSE QUARTZSMOKY QUARTZ

Luster General appearance of a mineral surface in reflected light General appearance of a mineral surface in reflected light Glassy-Obsidian

Hardness Resistance to scratching by different items; “scratchability” Resistance to scratching by different items; “scratchability” Mohs Hardness Scale >2 fingernail 3 penny 3 penny ~5 Steel of a pocket knife 5.5 Window Glass 6.6 Steel of a file 7 quartz crystal

Mohs Mineral Hardness Scale 1) Talc 2) Gypsum 3) Calcite 4) Flourite 5) Apatite 6) Feldspar 7) Quartz 8) Topaz 9) Corundum 10) Diamond Softest Hardest

Streak The color of a finely powdered mineral The color of a finely powdered mineral Determined by rubbing the mineral on a piece of unglazed porcelain (streak plate) Determined by rubbing the mineral on a piece of unglazed porcelain (streak plate)

Density The amount of matter in a given space (Mass/Volume) The amount of matter in a given space (Mass/Volume) Specific Gravity—comparing the density of the mineral to the density of water—what is the density of water? Specific Gravity—comparing the density of the mineral to the density of water—what is the density of water? The atomic structure and type of elements both determine the density The atomic structure and type of elements both determine the density

Crystal Shape Minerals have a characteristic crystal shape resulting from the atomic packing of the atoms when the mineral is forming Minerals have a characteristic crystal shape resulting from the atomic packing of the atoms when the mineral is forming

Cleavage and Fracture Cleavage is the tendency of a mineral to split or crack along parallel or flat planes Cleavage is the tendency of a mineral to split or crack along parallel or flat planes Fracture occurs when a mineral breaks at random lines instead of at consistent cleavage planes. Fracture occurs when a mineral breaks at random lines instead of at consistent cleavage planes. BIOTITE QUARTZ Obsidian No Cleavage 1 Direction of CleavageConchoidal Fracture

Special Properties Magnetism (Magnetite) Magnetism (Magnetite) Glowing under ultraviolet light (Fluorite) Glowing under ultraviolet light (Fluorite) Salty taste (Halite) Salty taste (Halite) Mica—one perfect cleavage Mica—one perfect cleavage Smell (Sulfur) Smell (Sulfur) Reaction to HCl (Calcite) Reaction to HCl (Calcite) Double Refraction—Icelandic Double Refraction—Icelandic Spar (A special type of Calcite) Magnetite

Minerals are classified into Families Silicates are the most abundant—Quartz and feldspar as well as mica and talc belong to this group. The colors vary as elements bond with the silicon and oxygen atoms Silicates are the most abundant—Quartz and feldspar as well as mica and talc belong to this group. The colors vary as elements bond with the silicon and oxygen atoms Carbonates form when 1 carbon atom bonds with 3 oxygen atoms. Metals ions may join producing charged atoms such as calcium carbonate which reacts with acid. Carbonates form when 1 carbon atom bonds with 3 oxygen atoms. Metals ions may join producing charged atoms such as calcium carbonate which reacts with acid. Gypsum is a member of the sulfate family Gypsum is a member of the sulfate family Oxide occur when oxygen joins with metals. Examples include pyrite and hematite. Oxide occur when oxygen joins with metals. Examples include pyrite and hematite. Halite is part of the halide family—metals plus non metals. Halite is part of the halide family—metals plus non metals.

Every American Requires 40,000 Pounds of New Minerals per Year at this level of consumption the average newborn infant will need a lifetime supply of: at this level of consumption the average newborn infant will need a lifetime supply of: -795 lbs of lead (car batteries, electric components) -757 lbs of zinc (to make brass, rubber, paints) -1500lbs of copper (electrical motors, wirings lbs aluminum (soda cans, aircraft) -32,700 lbs of iron (kitchen utensils, automobiles, buildings) -28,213 lbs of salt (cooking, detergents) -1,238,101 lbs of stone, sand, gravel, cement (roads, homes, etc.)