1. MINERALS Chapter 2

2. MINERALSBasic building block of rocksOver 4,000 minerals identifiedMineral Definition (requirements):1) Solid2) Naturally Occurring 3. Mineral Definition3) Inorganic no biologic origin4) Definite Chemical CompositionEx: Halite = NaCl Quartz = SiO2 4. Definite Chemical CompositionCan vary within limits Ex: Olivine = (Mg,Fe)2SiO4Mg and Fe can substitute for each other (Fig. 2.22) 5. Definite Chemical CompositionEx: Diamond = C (Carbon)Graphite = C (Carbon) 6. Mineral Definition5) Ordered Crystalline StructureEx: Halite (NaCl) 7. Ordered Crystalline StructureDiamond = high pressure- complex bonding of carbonatomsGraphite = low pressure- carbon atoms bond in sheets 8. Mineral Definition1) Solid2) Naturally Occurring3) Inorganic4) Definite Chemical Composition5) Ordered Crystalline Structure 9. Structure of Minerals1) Atom smallest building block of an elementComposed of atomic particles- protons (+) - neutrons - electrons (-) 10. Periodic Table of the Elements(p. 38) 11. AtomsAtomic Number = number ofprotons- defines which element atombelongs toAtomic Mass = sum of protons & neutrons 12. Balanced AtomsNumber of electrons = number ofprotonsRule:1st energy level = 2 electrons maxAll other energy levels = 8electrons max 13. AtomsValence electrons = electrons in outermost orbital shellAtoms bond b/c they want full outer shell of electrons 14. Types of Bonding1) Ionic BondingIon = atom with an electrical charge (+) or (-)- caused by losing or gaining electrons 15. Ionic BondingAtoms bond b/c opposites attract (like magnets)Ex: Halite (NaCl) 16. Types of Bonding2) Covalent Bonding- outer orbital shells overlap- atoms share valence electronsEx: Oxygen gas (O2) 17. Atomic Bonding3) Metallic bonding- valence electrons move freelybetween ions- accounts for high electricalconductivity 18. Structure of Minerals2) Element composed entirely of same kind of atoms - all atoms have same number of___________92 naturally occurring elements 19. ElementSome minerals are elements:Ex: Native CopperGoldSulfurGraphite 20. Structure of Minerals3) Compound combination oftwo or more elements- characteristics are different thanindividual elements Ex: Halite NaCl 21. CompoundMost minerals are compounds: Quartz = SiO2 Galena = PbS (lead sulfide) Hematite = Fe2O3 (iron oxide) Sphalerite = ZnS 22. Chemical Composition of Crust98.3% of crust composed of 8elements (Figure 2.19)Other 84 elements share 1.7% ofremaining crust- includes gold, zinc, lead, carbon,sulfur, silver, 23. Mineral Groups1) Silicate Group - 90% of all minerals Basic building block is the silica tetrahedron SiO44-(Si = silicon; Si+O = silica) 24. Silica tetrahedron (SiO44-)Negative charge bonds with positive ionsOther six abundant elements of crust are positive ions (Ex: K) 25. Mineral Groups2) Nonsilicate Group scarcecompared to silicatesIncludes:a) rock-forming minerals Ex: halite, gypsum, calcite 26. Nonsilicate Mineral Groupb) Native elementsEx: sulfur, copper, goldc) Metal oresEx: galena (PbS)magnetite (Fe3O4) 27. Nonsilicate Mineral Groupd) Industrial minerals Ex: fluorite, corundum 28. Silicate Mineral StructuresSilicate minerals have uniquesilica tetrahedra structures (Fig.2.21)- each structure is related to itscleavage patterns (or fracture) 29. Silicate Mineral StructuresBonds between silica tetrahedra are strongBonds between tetrahedra and positive ions are weakCleavage occurs between tetrahedra and positive ions 30. Types of Silicate Structures (Fig.2.23)Mineral StructureOlivine Isolated framework(Mg,Fe)2SiO4 No shared oxygensSi:O = 1:4No cleavage b/c (+) ions not in alignment 31. Types of Silicate StructuresMineralStructureAugiteSingle chain(Mg,Fe)SiO3 One oxygen is Si:O = 1:3 shared 32. Types of Silicate Structures Mineral StructureHornblende Double ChainTwo oxygens areshared 33. Types of Silicate StructuresMineral StructureBiotite &Sheet silicatesMuscovite(+) ions link sheets of tetrahedratogetherCreates one plane of cleavage 34. Types of Silicate StructuresMineral StructureQuartz 3-D frameworkSiO2 structure1:2All oxygen atoms are shared (nocleavage) 35. Silica rich vs. silica poorBased on Si:0 ratio- as more oxygen atoms areshared, the percentage of siliconin structure increases(compared to oxygen) 36. Silica rich vs. silica poorEx: silica poorOlivine (1:4) (Mg,Fe)2SiO4Ex: silica richQuartz (1:2) SiO2 37. Silicate MineralsHold clues to the environmental conditions where they formMinerals are stable when conditions are similar to where they formed 38. Environments:1) Magma crystallizing- quartz, feldspar, micasEx: Bowens Reaction Series 39. Environments:2) Weathering at surface- minerals that are unstable in newconditions at Earths surfacechange into claymineralsEx: kaolinite 40. Silicate Minerals3) Mountain building processes(high heat & pressure)Ex: garnet, micas 41. Economic Minerals(Nonsilicates)Metal OreOre = useful mineral that can be mined for a profit 42. Profitability depends upon:1) Concentration above the level of average crustal abundance (Figure 2.19)Lower crustal abundance = higher concentration necessary for profitability 43. ConcentrationEx: CopperCrustal abundance ~0.0135%Copper Ore = 50 times this amount 44. ConcentrationEx: AluminumCrustal abundance ~8.13%Aluminum ore (bauxite) = 4 times this amount 45. Profitability depends upon:2) Economic Changes- demand increases, so priceincreases- previously unprofitable depositsbecome profitable 46. Profitability depends upon:3) New technology:- decreases overhead costs- withdraws more mineral from therockEx: Gold mining with cyanide 47. Examples of metal ores:Hematite = Fe2O3 = iron oreSphalerite (Zn,Fe)S = zinc oreGalena = PbS = lead ore 48. RocksMixture of mineralsSome rx are impure quantities of the same mineral Ex: Limestone = calcite(rock)(mineral) 49. RocksMost rx are composed of several mineralsEx: Granite = quartz, feldspar, hornblende 50. 3 groups of rocks1)2)3)