Mineraloji Principles of Mineralogy and Ptography GEOE 207 GEOE 207 Principles of Mineralogy and Ptrography Principles of Mineralogy and Ptrography • Assist. Prof. Dr. FATMA TOKSOY-KÖKSAL • Office: 121 • Office Hours: 13:30-14:30 WednesdayLECTURE I INTRODUCTION and OUTLINES of the SUBJECT The goals of this course are to teach students to: The goals of this course are to teach students to: have an appreciation of the relationships among the structure of a mineral, its chemical composition, and its physical properties be able to identify samples of the common minerals and common rock types begin to understand factors that affect the stability and occurrence of minerals and assemblages of minerals ("rocks")COMPOSITION OF THE EARTH COMPOSITION OF THE EARTH The inner planets, including the Earth accreted from the Solar Nebula about 4.6 10 9 years ago After accretion compressed and became very hot due to gravity "Big Bang" Theory "Big Bang" Theory differentiated into a series of layers due to differences in densityCrust/Mantle/Core Earth layered structure heterogeneous composition High density material Ni-Fe metal alloys CORE Solid Inner CORE (Fe-Ni rich with minor S, K, and P) Lehman discontinuity Outer Liquid CORE (approximately same as inner core) Gutenberg discontinuity MANTLE dense Fe-Mg silicates CRUST lighter alumino-silicates (Mg-Fe; Na, K aluminosilicates) oceanic and continental Mohorovicic discontinuityCRUST extreme chemical differentiation during formation and evolution of Earth most of siderophile elements like Fe, Ni, Co, P in Earth’s core lithophile elements Si, Al, B,La, Ce, Na, K, Rb, Ca, Mn, U strongly fractionated out of the mantle and into the Earth’s crust considerable compositional differences btw the oceanic and continental crust oceanic crust continental crustEarth’s crust various rocks - Igneous plutonic, volcanic and hypabbysal from melts at high T, in liquid state - Sedimentary at surface conditions of Low P & T from aqueous solutions - Metamorphic at depth at higher P & T due to changes in solid state GENERAL CLASSIFICATION OF ROCKS Earth Earth’ ’s s crust crust 95% igneous rock (or it's metamorphic equivalent) e.g. basalt, granite, granitic gneiss, schist... 8 most abundant elements in crust = (99 wt % and approx. volume) composition O, Si, Al, Fe, Ca, Na, K, Mg most common crustal minerals silicates e.g. quartz SiO 2 aluminosilicates e.g., K-feldspar (orthoclase) KAlSi 3 O 8 oxides e.g., hematite Fe 2 O 3 Total earth Total earth composition composition 99% Fe, O, Si, Mg, Ni, S, Ca, Al difference due to core and mantlerocks rocks dealt with PETROGRAPHY minerals minerals building blocks of the rocks dealt with MINERALOGY PART I: MINERALOGY PART I: MINERALOGY INTRODUCTION minerals subject of MINERALOGY MINERA Latin word LOGOS >2500 minerals 200 known most common and abundant (from the Earth crust) Greek word (knowledge) Mineralogy mature science science of mineralogy study of the physics and chemistry of natural, solid, crystalline materialsWhy Study Minerals? Why Study Minerals? Minerals fundamental to Environmental sciences Earth Sciences Geochemsitry Geophysics the way atoms arranged in rocks Atomic environments in rock homogeneous from the mm scale to the Å scale (7 orders of magnitude) Rocks aggregates of minerals Mineralogy solid-state geochemistryDEFINITION OF MINERAL DEFINITION OF MINERAL MINERAL naturally occurring homogeneous solid definite (not fixed) chemical composition an ordered atomic arrangement formed by inorganic processes mineral a natural, crystalline phase a chemical compound must occur naturally somewhere and be stable enough to study in the lab Minerals Naturally Occurring distinguishes man-made substances e.g. synthetic (eg. synthetic diamond) many compounds made in the lab that are not minerals unless not found in natureMinerals Homogeneous solid chemically homogeneous down to the atomic scale means consists of a single, solid substance not be divided into simpler chemical compounds excludes gases and liquids H 2 O a mineral but as water not a mineral as ice in a glacier liquid Hg but in some ore deposits Mineraloid Minerals Definite, but not fixed, composition specific but variable chemical formula CaMg(CO 3 ) 2 Mg ?Fe,Mn generally Ca(Mg 0.7 Fe 0.2 Mn 0.1 )(CO 3 ) 2 dolomite opal indefinite chemical composition SiO 2 .nH 2 O mineraloid for a given mineral substitutions of similar elements possibleoriginal crystallinity destroyed by radiation from radioactive elements present in the original structure Minerals an ordered atomic arrangement chemical formulas determined by the atomic structures an internal structural framework of atoms (or ions) arranged in a regular geometric pattern = Crystalline solid repeated patterns in 3-D position of an atom in the structure definite predictable crystals periodic arrays of atoms Solids lack an ordered atomic arrangement Amorphous eg. volcanic glass, limonite and Metamict minerals (e.g Zir in Bio) Cl Cl Cl Cl Cl Cl Cl Cl Na NaMinerals Inorganic Processes at least one occurrence formed by inorganic processes inorganic in origin but some biogenically produced inorganic compounds means e.g. calcite by organisms to form shells also in igneous and metamorphic environments but e.g. aragonite in shell and pearl opal, Mt, fluorite, some phosphates, sulphates and Mn-oxides Py and elemental S of bacterial origin not mineral However organic compounds petroleum and coal (macerals)Minerals Minerals • Gold, silver, diamond, graphite • Pyrite, marcasite, sphalerite • Salt (halite), fluorite, calcite, apatite • Olivine, garnet, zircon • Pyroxene, amphibole, mica • Quartz, feldspar, zeolite natural solids natural solids ---- ---- NOT Minerals NOT Minerals • Granite, basalt, limestone (rocks) • Wood, coal (organic, noncrystalline) • Opal, obsidian, pumice (glass, noncrystalline) Mineralogy requires an understanding of: Mineralogy requires an understanding of: chemistry - elements, electronic structure, bonding, chemical analyses; forms of x-tals physics - physical properties (density, electrical properties, cleavage, hardness, magnetic properties, etc.) crystallography - the structure of minerals - internal & external; geometry and trigonometry; symmetry interrelationships between humans and their natural environment mineral genesis - environments of formation (e.g., ocean floor vs. subduction zone) determinitive mineralogy - physical and chemical testing; analytical equipment classification schemesGENERAL CLASSIFICATION OF MINERALS GENERAL CLASSIFICATION OF MINERALS Rock Forming Minerals rocks consist of various minerals useful for industry (eg. Feldspar ›Ceramics, Glass) Industrial Minerals Ore Minerals high concentrations of metallic elements (eg. chalcopyrite-Cu; Cinnabar-Hg) metals and valuable elements extracted Gemstones for decorative purposes (eg. Diamond, Ruby, Emerald) Gemstones Secondary minerals rock forming minerals are decomposed and altered when HT/HP rocks brought to surface (LT/LP) by tectonic forces e.g. Clay minerals, Serpentine minerals etcNAMING OF MINERALS NAMING OF MINERALS physical property magnetic ›Magnetite (Fe 3 O 4 ) predominant element Cr ›Chromite (FeCr 2 O 4 ) Ba ›Barite (BaSO 4 ) locality Franklin, New Jersey ›Franklinite (ZnFe 2 O 4 ) Panderma (Bandırma) ›Pandermite (Ca 4 B 10 O 19.7 H 2 O) colour Albus (L. white) ›Albite (NaAlSi 3 O 8 ) Rhodon (G. rose) ›Rhodonite (MnSiO 3 ) scientist Benjamin Silliman ›Sillimanite (Al 2 SiO 5 )CRYSTALLIZATION CRYSTALLIZATION Crystals from solutions, melts and vapours disordered states random distribution change in T, P, Conc. atoms join in an ordered arrangement Crystalline State Crystallization from solutions: evaporation of water from NaCl soln soln more Na + & Cl - per unit volume remaining water not hold all the salt in the soln precipitation of solid salt slow evaporation few centers of crystallization big crystals rapid evaporation many centers of crystallization small crystals P or T increase dissolve more salt into solvent by forcing solvent into crystal str increase in thermal vibrations breaking ionic bonds P or T decrease saturated soln supersaturation crystallizationCrystallization from melt: much the same process as from a soln rock melt (magma) uncombined ions with considerable amount of cross-linking of ions or ionic groups [SiO 4 ] 4- ions free to move in any direction in molten state cooling magma two opposing tendencies (1) Thermal vibrations tending to destroy nuclei of potential minerals (2) Attractive forces tending to aggregate ions into X-str decrease of T and P in a "wet" melt decrease of T and increase of P in a "dry" melt eliminates destructive effect of (1) increase attractive effect of (2) crystallization Crystallization from vapour phase solid crystals without the intervening liquid phase from vapours eg. sublimates of S formed near volcanic ventsCRYSTAL CRYSTAL GROWTH GROWTH crystal growth first stage nucleation random formation of large number of potential nuclei unstable high surface energy=surface area/volume small nuclei high surface area many atoms on the outer surface with unsatisfied bonds in saturated soln most nuclei redissolve SO if a nucleus survive grow rapidly enough to increase its volume to reduce its surface energy internal atoms have completely satisfied bonds reach a critical size the nucleus survives grows at a relatively diminished rate--- In ionically bonded crystal v during crystal growth ordered accretion of ions where surface energy greatest --- unsatisfied bond --- corner --- max --- edge --- intemediate --- surface --- minimum --- In non-ionically bonded crystal v atoms accrete on outer surface as clumps of atoms v steps along which new outer layer of crystalCHEMICAL BONDS AND CLASSIFICATION OF MINERALS CHEMICAL BONDS AND CLASSIFICATION OF MINERALS CHEMICAL BONDS CHEMICAL BONDS forces binding atoms, ions or ionic groups electrical in nature forces bonds responsible for most mineral properties five principle types covalent ionic metallic hydrogen van der Waals strength covalent covalent electron sharing atoms inert gas configuration elements near the middle of the periodic table C, Si, Al, S 2, 3, and 4 vacancies in outer electron orbitals up to four covalent bonds with neighbouring atoms minerals with covalent bonds insoluble, great stability very high melting points2 Cl atoms e - = 1s 2 2s 2 2 p 6 3s 2 3p 5 overlap an outer orbital, perhaps can share whereby 2 e- "fill" the remaining 3p shell of each Cl in a strong bond › Cl 2 shared e- bond C four valance electrons each C atom fill the bonding orbitals by electron sharing with four other C atoms forming very stable firmly bonded configuration tetrahedron shape with a central C atom bonded to 4 others at apices very rigid structure diamond C-C-C bond angle fixed at 109 o 28'ionic ionic atoms strong tendency to achieve inert gas configuration with completely filled valence shell of an atom tranferred to that of another one Na (1s 2 2s 2 2p 6 3s 1 ) › Na + (1s 2 2s 2 2p 6 ) + e - Cl (1s 2 2s 2 2p 6 3s 2 3p 5 ) › Cl - (1s 2 2s 2 2p 6 3s 2 3p 6 ) electron lost by Na picked by Cl attraction btw Na + and Cl - ionic or electrostatic bond moderate hardness and specific gravity fairly high melting point easily disrupted by polarized solvents (water) poor electrical and heat conductors bond length inter ionic distance shorter bond length, stronger bond reverse relation btw melting point bond strenght reverse relation btw melting point reverse relation btw hardness linear relation btw bond strenght and charge numbermetallic metallic electrons freely move through the crystal structure no affinity to any particular nucleus without disrupting the bonding mechanism very weakly tied valence electrons into metal structure in metal-X’s positively charged metal ions with their filled electron orbitals surrounded with a (-)ly charged dense cloud of valence electrons occurs in native metal minerals such as Au, Ag, Cu high conductivity, ductility generally low hardnesshydrogen hydrogen form X-structure by attraction btw oppositely charged ends of molecules polar molecules electrostatic bond btw (+)ly charged H + and (-)ly charged ions (O 2- , N 3+ ) shape of H 2 O molecule polar when crystallized ice mineral each O atom is bonded to 4 neighbouring O atoms in a tetrahedral arrangement, by intervening hydrogen bonds common in hydroxide mineral group (OH) - group not behave strickly as spherical anionic group asymmetric and polar dipole effect in many of layered silicates with hydroxyl group (micas and clays)cov cov VdW VdW van Der Waals van Der Waals usually btw electrically neutral molecules Cl 2 , N 2 , O 2 molecular solids occupied valence orbitals by electrons used in covalent bonding polarization of an atom or a molecule dipole effect residual charge on the surfaces neutral atoms or molecules into a cohesive structure van der Waals or residual bond graphite and crystalline sulphur in graphite covalently bonded van der Waals covalent bond well developed cleavage low hardness in sulphur S8 rings C6 rings covalently bonded adjacent rings van der Waals low hardness low melting pointCRYSTALS WITH MORE THAN ONE BOND TYPE minerals with only one type of bonding rare most two or more bond types most graphite strong covalent bonding weak van der Waals bonding high melting point perfect cleavage layered silicates sheets of strongly bonded silica tetrahedral layers relatively weak ionic and/or hydrogen bonds + perfect basal cleavageCHEMICAL CLASSIFICATION OF MINERALS O most abundant element chemically minerals considered as oxides principally Si second most abundant element great affinity btw O and Si strong covalent bonding silica tetrahedron (SiO 4 ) 4- (SiO 4 ) 4- balanced by various cations as in Mg 2 SiO 4 mineral group silicates other cations join with O oxides e.g. Mt --- Fe 3 O 4O oxyanion minerals with close packing of O 2- with small interstitial cations depending on type of interstitial cations OXYANION MINERALS Oxyanions Example CARBONATES [CO 3 ] -2 Calcite CaCO 3 NITRATES [NO 3 ] -2 Niter KNO 3 SULPHATES [SO 4 ]- 2 Gypsum CaSO 4 .2H 2 O CHROMATES [CrO 4 ] -2 Crocoite PbCrO 4 MOLYBDATES [MoO 4 ] -2 Wulfenite PbMoO 4 TUNGSTATES [WO 4 ] -2 Scheelite CaWO 4 BORATES [B 3 O 4 (OH) 3 ] -2 Colemanite CaB 3 O 4 (OH) 3 .H 2 O PHOSPHATES [PO 4 ] -3 Apatite Ca 5 (PO 4 ) 3 (F,Cl,OH) ARSENATES [AsO 4 ] -3 Erythrite Co 3 (AsO 4 ).8H 2 O VANADATES [VO 4 ] -3 Vanadinite Pb 5 (VO 4 ) 3 Cl URANYLATES [UO 2 ] +2 Carnotite K 2 (UO 2 ) 2 (VO 4 ) 2 .3H 2 OO strong ionic bond with H + hydroxide minerals hydroxyl anion (OH) - e.g. Brucite Mg(OH) 2 , Goethite FeO(OH) S next important anion combination with metallic cations sulphides e.g. Galena PbS, Sphalerite ZnS, Chalcopyrite CuFeS 2 Halogens of Cl and F halides e.g. Halite NaCl, Fluorite CaF 2 native elements not form any chemical compounds as elements noble elements with metallic bonds e.g. Au, Ag, Pt native metals semimetals with bond type btw covalent and metallic native semimetals e.g. As, Bi non-metals with mixed types of bonding native nonmetals e.g. C, S