Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Minerals, Rocks, and Mineral Resources Chapter 7

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Mineral Properties Earth’s crust composed of minerals Naturally occurring, crystalline, inorganic substances ◦Have unique physical and chemical properties ◦Naturally occurring refers to formation process ◦Crystalline—atoms and molecules are in patterns ◦Inorganic—not formed from a living thing

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Mineral Properties (continued) Physical and chemical properties Used to help identify the mineral ◦Color—not sufficient itself for identification ◦Luster—way it reflects light ◦Streak—small powder trail left when rubbed ◦Hardness—resistance to being scratched

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Mineral Properties (continued) Cleavage—breaks along surface or plane Specific gravity—mineral’s relative density Chemical tests Magnetism Luminescence Production of electrical current Flame color when exposed to fire

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Mineral Composition Composed of specific elements giving unique properties Most made of silicon and oxygen ◦Most abundant elements in Earth’s crust ◦Silicon and oxygen form silicates Other elements that compose minerals: ◦Aluminum– Iron – Calcium ◦Sodium– Magnesium – Potassium

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Structure of Silicate

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Rocks and Minerals Only one specific mineral ◦Called monomineralic rock ◦Rock salt made of the mineral halite ◦Limestone made of the mineral calcite More than one mineral ◦Called polymineralic rock Most rocks on Earth’s crust are polymineralic

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Rocks Naturally formed Solid material making up Earth’s crust Classified on basis of origin and formation Three main categories: ◦Igneous ◦Sedimentary ◦Metamorphic

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Rocks (continued) Igneous—cooling and solidification of molten rock ◦Process is called crystallization ◦Can be intrusive or extrusive ◦Identified by:  Texture Color  Density Mineral composition ◦Usually formed from intrusive molten rock

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Rocks (continued) If cooled quickly forming very small crystals—called extrusive Color is either light or dark ◦Felsic rocks—high amounts of quartz and potassium feldspar  Light in color with low density ◦Mafic rocks—high amounts of pyroxine, olivine, and plagioclase  Dark in color with high density

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Rocks (continued) Sedimentary—formed from accumulation of sediments ◦Often classified by texture  Either clastic or crystalline ◦Clastic—individually bonded rock fragments ◦Crystalline—rock is composed of crystals ◦Bioclastic—formed under remains of living organisms

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Rocks (continued) Usually horizontally arranged parallel layers called strata Only type of rock containing fossils Process of turning into solid rock— lithification ◦Cementation ◦Compression and compaction ◦Chemical processes—precipitation and evaporation ◦Living organisms or plant remains

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Rocks (continued) Metamorphic—undergo intense heat and pressure ◦Become foliated—form distinct layers ◦Often show a distorted structure  Folding or curving ◦Often located within igneous or sedimentary rocks ◦Classified by:  Composition Foliation Texture

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Rock Cycle

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Mineral Resources Naturally existing mineral, compound, or pure element ◦Used by humans in some way Metallic: ◦Existing in large quantities:  Iron, Aluminum, Magnesium,Titanium, and Manganese ◦Scarce metals:  Gold, Silver, Copper, Zinc, Lead, Tin, and Nickel

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Mineral Resources (continued) Nonmetallic resources: ◦Construction materials:  Gravel Sandstone  Shale Limestone ◦Others include:  Phosphates  Sulfur  Sodium chloride

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Mineral Deposits Four different processes ◦Igneous  Volcanic activity, intrusive magma, near hydrothermal vents ◦Sedimentary  Precipitation and evaporation ◦Weathered deposits  Result of leaching

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Mining Techniques Two broad categories: ◦Underground mining ◦Surface mining  Open pit—open up the surface to excavate  Strip mining—excavate shallow strips along surface  Hydraulic mining—high-pressure blast of water  Dredging—when below water