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MINERALS Introduction What Are They?
Physical Properties & Identification Atoms & Elements Mineral Groups
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Minerals Introduction
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Eight Most Abundant Elements in Earth’s Crust
GEOL 131: Minerals - Intro Eight Most Abundant Elements in Earth’s Crust
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GEOL 131: Minerals - Intro
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Some of the Most Abundant Minerals in Earth’s Crust
GEOL 131: Minerals - Intro Some of the Most Abundant Minerals in Earth’s Crust Quartz Feldspars Micas
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Some of the Most Abundant Minerals in Earth’s Crust
GEOL 131: Minerals - Intro Some of the Most Abundant Minerals in Earth’s Crust Amphiboles Pyroxenes Olivine e
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Minerals Minerals What Are They?
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Minerals Are: Solid Naturally occurring Inorganic
GEOL 131: Minerals – What Are They? Minerals Are: Solid Naturally occurring Inorganic
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Minerals Have: Well-defined chemical compositions
GEOL 131: Minerals – What Are They? Minerals Have: Well-defined chemical compositions Well-ordered atomic structures
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Physical Properties & Identification
Minerals Physical Properties & Identification
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Physical Properties Each mineral has a unique set of properties
GEOL 131: Minerals – Physical Properties & Identification Physical Properties Each mineral has a unique set of properties Determined by mineral’s chemical composition and atomic structure Properties are used to identify unknown minerals
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Physical Properties Commonly Used in Identification
GEOL 131: Minerals – Physical Properties & Identification Physical Properties Commonly Used in Identification Color Streak Luster Cleavage Crystal habit Striations Hardness Effervescence Magnetism
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COLOR Easy to observe, but can be misleading
GEOL 131: Minerals – Physical Properties & Identification COLOR Easy to observe, but can be misleading Impurities can produce different colors Quartz
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STREAK Color of powdered mineral More reliable than “bulk” color
GEOL 131: Minerals – Physical Properties & Identification STREAK Color of powdered mineral More reliable than “bulk” color Streak plate
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LUSTER How sample reflects light Not the same as color
GEOL 131: Minerals – Physical Properties & Identification LUSTER How sample reflects light Not the same as color NONMETALLIC luster METALLIC luster
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LUSTER How sample reflects light Not the same as color
GEOL 131: Minerals – Physical Properties & Identification LUSTER How sample reflects light Not the same as color Both of these minerals have a METALLIC luster
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CLEAVAGE How sample cleaves (breaks)
GEOL 131: Minerals – Physical Properties & Identification CLEAVAGE How sample cleaves (breaks) Always the same for a given mineral Three aspects Quality Number of directions Angle
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CLEAVAGE QUALITY - None
GEOL 131: Minerals – Physical Properties & Identification CLEAVAGE QUALITY - None No cleavage: irregular breakage surface
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CLEAVAGE QUALITY - Good
GEOL 131: Minerals – Physical Properties & Identification CLEAVAGE QUALITY - Good Note “stair-step” pattern Good cleavage: somewhat regular breakage surface
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CLEAVAGE QUALITY – Excellent/perfect
GEOL 131: Minerals – Physical Properties & Identification CLEAVAGE QUALITY – Excellent/perfect Excellent cleavage: smooth breakage surface
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# OF CLEAVAGE DIRECTIONS
GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS A number Only applies to good or excellent cleavage quality
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# OF CLEAVAGE DIRECTIONS - One
GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS - One One smooth surface
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# OF CLEAVAGE DIRECTIONS - Two
GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS - Two Two non-parallel smooth surfaces
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# OF CLEAVAGE DIRECTIONS - Three
GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS - Three Three non-parallel smooth surfaces
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# OF CLEAVAGE DIRECTIONS - Four
GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS - Four Fluorite Four non-parallel smooth surfaces
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CLEAVAGE ANGLE Angle between cleavage surfaces 60-degree angle
GEOL 131: Minerals – Physical Properties & Identification CLEAVAGE ANGLE Angle between cleavage surfaces 60-degree angle 90-degree angle 120-degree angle
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CRYSTAL HABIT How a mineral grows
GEOL 131: Minerals – Physical Properties & Identification CRYSTAL HABIT How a mineral grows Unusual to see well-formed crystals in nature Need space to grow
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CRYSTAL HABIT Well-formed crystal faces
GEOL 131: Minerals – Physical Properties & Identification CRYSTAL HABIT Well-formed crystal faces Poorly-formed crystals: not enough space
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GEOL 131: Minerals – Physical Properties & Identification
CRYSTAL HABIT Don’t confuse a crystal face with an excellent cleavage surface Crystal face – caused by growth Cleavage surface – caused by breaking
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STRIATIONS Thin grooves on mineral’s surface Can be hard to see
GEOL 131: Minerals – Physical Properties & Identification STRIATIONS Thin grooves on mineral’s surface Can be hard to see From facweb.bhc.edu From www4.uwm.edu
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GEOL 131: Minerals – Physical Properties & Identification
HARDNESS
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EFFERVESCENCE If CO3 ion present, carbon dioxide bubbles will form:
GEOL 131: Minerals – Physical Properties & Identification EFFERVESCENCE Dilute hydrochloric acid (HCl) If CO3 ion present, carbon dioxide bubbles will form: CaCO3(calcite) + 2HCl = H2O + CO2 + CaCl2
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Magnetite (Fe3O4) attracting a magnet
GEOL 131: Minerals – Physical Properties & Identification MAGNETISM Some iron-rich minerals are magnetic Magnetite (Fe3O4) attracting a magnet
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MINERAL IDENTIFICATION
GEOL 131: Minerals – Physical Properties & Identification MINERAL IDENTIFICATION Table or flowchart Observation of unique properties Narrow down possibilities
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MINERAL IDENTIFICATION
GEOL 131: Minerals – Physical Properties & Identification MINERAL IDENTIFICATION
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Minerals Atoms & Elements
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All Minerals Are Made of Atoms
GEOL 131: Minerals – Atoms and Elements All Minerals Are Made of Atoms
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GEOL 131: Minerals – Atoms and Elements The Periodic Table of the Elements
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Basic Structure of an Atom
GEOL 131: Minerals – Atoms and Elements Basic Structure of an Atom
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GEOL 131: Minerals – Atoms and Elements
Valence Shells
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Atomic Bonds Hold atoms together to make mineral crystals
GEOL 131: Minerals – Atoms and Elements Atomic Bonds Hold atoms together to make mineral crystals Formed by electron interaction Require filled valence shells
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GEOL 131: Minerals – Atoms and Elements
Atomic Bonds
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GEOL 131: Minerals – Atoms and Elements
Atomic Bonds
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Chemical Composition of Minerals
GEOL 131: Minerals – Atoms and Elements Chemical Composition of Minerals Elements present and in what amounts Well-defined: Limited or no variation Described by mineral’s formula Halite (salt): NaCl
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Atomic Structure of Minerals
GEOL 131: Minerals – Atoms and Elements Atomic Structure of Minerals Arrangement of atoms Well-ordered: Repeats in a regular pattern
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Atomic Structure of Minerals
GEOL 131: Minerals – Atoms and Elements Atomic Structure of Minerals Arrangement of atoms QUARTZ
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Atomic Structure – Diamond vs Graphite
GEOL 131: Minerals – Atoms and Elements Atomic Structure – Diamond vs Graphite
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MINERAL GROUPS Silicates (largest group) Carbonates Sulfates Sulfides
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS Silicates (largest group) Carbonates Sulfates Sulfides Oxides Halides Native elements
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MINERAL GROUPS - Silicates
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS - Silicates Largest group 90% of Earth’s crust Si and O atoms in a tetrahedron (pyramid)
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MINERAL GROUPS - Silicates
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS - Silicates Oxygen atoms can bond to adjacent tetrahedra in a mineral’s atomic structure Forms the “backbone” of the mineral Example: single-chain structure Each tetrahedron shares two oxygens with adjacent tetrahedra
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MINERAL GROUPS - Silicates
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS - Silicates Silicate structures
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MINERAL GROUPS - Silicates
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS - Silicates A silicate mineral’s properties depend partly on its silicate structure Hardness: 3-D networks make harder minerals (quartz) Cleavage: sheet structures produce sheet cleavage (micas)
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MINERAL GROUPS - Silicates
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS - Silicates Example: Hardness 3-D frameworks make harder minerals Quartz
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MINERAL GROUPS - Silicates
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS - Silicates Example: Cleavage Sheet structures produce sheet cleavage Micas
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MINERAL GROUPS - Silicates
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS - Silicates Dark vs. light silicates Dark: rich in Fe and Mg Light: little Fe or Mg Important for igneous rocks (next chapter)
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MINERAL GROUPS - Silicates
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS - Silicates Some common silicate minerals Quartz: SiO2 Orthoclase feldspar (aka potassium feldspar or K-spar): KAlSi3O8 Muscovite mica: KAl2(AlSi3O10)(F,OH)2 Hornblende: Ca2(Mg, Fe, Al)5 (Al, Si)8O22(OH)2
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MINERAL GROUPS – Carbonates
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS – Carbonates CO3 ion Effervescence Common examples Calcite: CaCO3 Dolomite: CaMg(CO3)2 Malachite: Cu2CO3(OH)2 Malachite
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MINERAL GROUPS – Sulfates
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS – Sulfates SO4 ion Common examples Gypsum: CaMgSO4*2H2O Anhydrite: CaMgSO4 Barite: BaSO4 Giant gypsum crystals, Naica Mine, Mexico
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MINERAL GROUPS – Sulfides
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS – Sulfides S, no oxygen Important metal ores Common examples Galena: PbS Pyrite: FeS Chalcopyrite: CuFeS2 Cubic galena crystals
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MINERAL GROUPS – Oxides
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS – Oxides Oxygen No Si, C, or S Common examples Hematite: Fe2O3 Magnetite: Fe3O4 Corundum: Al2O3 Red corundum (ruby)
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MINERAL GROUPS – Halides
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS – Halides Cl, F, or Br Common examples Halite (salt): NaCl Fluorite: CaF2 Wieliczka salt mine, Poland
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MINERAL GROUPS – Native elements
GEOL 131: Minerals – Mineral Groups MINERAL GROUPS – Native elements Any element in pure form Common examples Sulfur (S) Graphite (C) Copper (Cu)
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End of Minerals chapter
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