A mineral is a naturally occurring, inorganic solid that has a crystal structure and a definite chemical composition.
Naturally Occurring Formed by processes that occur in the natural world
Inorganic Not formed from materials that were once part of a living thing.
Solid Solid, with a definite volume and shape.
Crystal structure Particles of a mineral line up in a pattern that repeats over and over again. Flat sides are called faces
Definite Chemical Composition Always contains certain elements in definite proportions. Example quartz has one atom of silicon for every two atoms of oxygen (SiO 2 )
Identifying Minerals Each mineral has characteristic properties that can be used to identify it.
Color Color is easily observed but alone provides too little information to make an identification Observe surface of mineral
Streak The color of its powder Streak color and mineral color are often different Observe color of powder on unglazed tile
Luster How light is reflected from a mineral s surface. Observe how mineral reflects light
Density Mass in a given space No matter the sample size, density is the same Find mass per unit volume
Hardness Mohs hardness scale 10 minerals from softest to hardest Perform a scratch test
Crystal Systems Crystals grow atom by atom to form that mineral s crystal structure Geometric shape Observe number and angle of crystal faces
Cleavage and Fracture The way a mineral breaks apart Break mineral apart to see if it splits along flat surfaces.
Special properties Special or unique physical property Examples include magnetism, fluorescence, optical properties
Luster Metallic - Galena Glassy - Topaz Waxy, Greasy or Pearly Talc
Luster Submetallic or dull - Graphite Silky - Malachite Earthy - Hematite
Mohs Hardness Scale 1. Talc flakes when scratched by a fingernail 2. Gypsum a fingernail can easily scratch it 3. Calcite a fingernail can t scratch it but a penny can
Mohs Hardness Scale 4. Fluorite a steel knife can easily scratch it 5. Apatite a steel knife can scratch it 6. Feldspar It can t be scratched by a knife but it can scratch window glass
Mohs Hardness Scale 7. Quartz it can scratch steel and hard glass easily 8. Topaz It can scratch quartz easily 9. Corundum It can scratch topaz
Mohs Hardness Scale 10.Diamond The hardest known material. It can scratch all other materials
Cubic Examples: Magnetite, Halite, Garnet
Hexagonal Six sided Examples: Beryl, apatite, Quartz
Tetragonal Two sides the same, one different Examples: Zircon, Rutile
Orthorhombic Three different Lengths Example: Sulfur
Monoclinic (Rectangle pushed over) Example: Azurite, Gypsum
Triclinic (rectangle pushed over twice) Example: Feldspar
How Minerals Form Minerals from magma and lava Magma below the surface Deep down it cools slowly large crystals Toward surface it cools rapidly small crystals Lava on surface Cools quickly small crystals
Minerals From Solutions Solution a mixture in which one substance is dissolved in another
Minerals From Solutions Evaporation water evaporates and the crystals are left behind Examples: salt, halite, gypsum, calcite
Minerals From Solutions Hot water solutions: Magma heats water, when water cools the elements leave the solution and crystallize as minerals Example: silver
Uses of Minerals
Gemstones Valued for color, luster and durability Used for decoration (jewelry) Also used for grinding and polishing in manufacturing.
Metals Not as hard as gemstones Used for wire, rolled into sheets and can be molded into useful shapes
Other useful minerals Foods, medicines, fertilizers and building materials Quartz glass Gypsum drywall, cement Talc talcum powder
Producing Metals from Minerals
Prospecting Observe rocks on surface Maps made of rocks beneath by measuring earth s magnetic field
Mining Strip mines scrape away soil Open pit mines giant pits Shaft mines follow veins, network of tunnels
Smelting Ore is mixed with other substances then melted and the useful minerals are separated from other elements.
Further Processing Add other elements to the metal to make an alloy Example carbon + iron = steel