1Earth Materials: Minerals• What is a mineral?• Properties/characteristics of different types of minerals1• Mineral structures and bonding• Major categories of minerals• Importance and uses of mineralsWhat is a mineral?A substance must meet 5 requirements to be classified as a mineral2Mineral PropertiesThree general categories:Optical3PhysicalChemicalMineral PropertiesSome optical propertiesColorStreak4StreakLusterDouble refractionFluorescenceTransmission of light (transparent, translucent, or opaque)2Minerals of various colorsUnderstanding Earth5StreakExample: hematiteFig 2.26 Understanding Earth6Metallic luster: gold and pyrite7Non-metallic luster: feldspar, mica, olivine, and quartzDouble refraction in a transparent piece of calcite83Mineral PropertiesSome physical propertiesHardness 9DensityCrystal shapeHow it breaks: cleavage and fracture10Understanding Earth11Crystal of galena (left) (lead sulfide)Crystal of quartz (right) (silicon dioxide)These minerals differ in color, luster, light transmission, crystal form, hardness, cleavage, and streak.Fig 2.10 Understanding EarthMineral PropertiesHow a mineral breaks:Fracture12Cleavage- key observations for cleavage:- numberof directions- anglesbetween them413Conchoidal fracture in obsidianFig 4.3 Understanding Earth14Cleavage of mica into thin sheetsFig 2.23 Understanding EarthCleavage in calciteFig 2.24 Understanding Earth1516Fig 2.25 Understanding Earth5Mineral PropertiesChemical propertiesAcid test Salty taste Many other chemical tests17Fig 2.22 Understanding EarthMineral PropertiesSome other propertiesHabitMti18Magnetism Absorbs waterSmellSome unusual crystalHabitsGeology2ndedbarite rosettes(barium sulfate)needles of stibnite(antimony sulfide)19Geology2ed.Chernicoffstellate pyrite(iron sulfide)botryoidal malachite (green) with azurite (blue)(hydrous copper carbonates)In-class exercise20Working in groups, examine and describe the properties of each mineral sample provided6Mineral PropertiesRelationship to:21atomic compositionatomic structure and bondingMineral PropertiesChemical bonds - how multiple atoms are held togetherioniclt22covalentmetallicother types of bonding23Graphite and DiamondBoth are composed of carbon but have very different properties. Fig 2.15 Understanding EarthCarbon atomFig 2.2 Understanding Earth247Structures of25Structures of graphite (left) and diamond (right)Geology 2nded. - ChernicoffStructure of halite (sodium chloride -salt)Fig 2.16 Understanding Earth26Ionic bonds hold together Cl-1and Na +1+1-127Regular arrangement of atoms in galena (left)Cube-shaped crystals (below)The structure of galena is essentially the same as in halite. Therefore, both grow and break to form cubes. Their color and luster are different, however, because they have different compositions (and bonding).Fig 2.10 Understanding EarthUnderstanding Earth288Some major groups of mineralsSilicates e.g. quartz, feldspar, mica, olivineNon-silicates:Carbonatese.g. calcite29Carbonatese.g. calciteOxides e.g. magnetite, hematiteSulfides e.g. pyrite, galenaSulfates e.g. gypsumNative elements e.g. native gold, copperHalides e.g. halite30Silicon-oxygen tetrahedronFig 2.16 Understanding Earthildoublesheets31Types of silicate mineral structuresFigs 2.17 and 2.18 Understanding Earthindividualtetrahedrasingle chainsdouble chainssheets3-D frameworksMica is built from numerous sheets. This explains the single direction of cleavage found in micas.32Geology 2nded. - ChernicoffMuscovite Mica9Importance of Minerals• Almost all rocks are made of minerals!• Aesthetic value •Natural resourcevalue33•Natural resource valueMinerals in GraniteMinerals as Constituents of Rocks34Native goldSmithsonianAesthetic valueA large cut diamondSmithsonian35Iron ores36Fig 22.10 Understanding Earth10A great deal of effort goes into obtaining key mineral resources37Open pit copper mine south of Tucson, ArizonaFig 22.22 Understanding EarthU.S. reliance on imported mineral resourcesFig 22.17 Understanding Earth38U.S. reliance on imported mineral resourcesFig 22.17 Understanding Earth39Some Online ResourcesMineral resources info. from the USGShttp://minerals.er.usgs.gov/http://minerals.er.usgs.gov/minerals/http://www.usgs.gov/science/science.php?term=745WebMineral Minerals Databasehttp://www.webmineral.com/MinDat Minerals Databasehttp://www mindat org/40http://www.mindat.org/Smithsonian Gem & Mineral Collectionhttp://www.gimizu.de/sgmcol/Smithsonian Department of Mineral Scienceshttp://www.minerals.si.edu/More rock and mineral links (some with lesson plans)http://edtech.kennesaw.edu/web/rocks.htmlhttp://www.dlese.org/dds/browse_su_0k.htm (Digital Library for Earth System