MINERALS Introduction What Are They? Physical Properties & Identification Atoms & Elements Mineral Groups

Minerals Introduction

Eight Most Abundant Elements in Earth’s Crust GEOL 131: Minerals - Intro Eight Most Abundant Elements in Earth’s Crust

GEOL 131: Minerals - Intro

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

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

Minerals Minerals What Are They?

Minerals Are: Solid Naturally occurring Inorganic GEOL 131: Minerals – What Are They? Minerals Are: Solid Naturally occurring Inorganic

Minerals Have: Well-defined chemical compositions GEOL 131: Minerals – What Are They? Minerals Have: Well-defined chemical compositions Well-ordered atomic structures

Physical Properties & Identification Minerals Physical Properties & Identification

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

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

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

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

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

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

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

CLEAVAGE QUALITY - None GEOL 131: Minerals – Physical Properties & Identification CLEAVAGE QUALITY - None No cleavage: irregular breakage surface

CLEAVAGE QUALITY - Good GEOL 131: Minerals – Physical Properties & Identification CLEAVAGE QUALITY - Good Note “stair-step” pattern Good cleavage: somewhat regular breakage surface

CLEAVAGE QUALITY – Excellent/perfect GEOL 131: Minerals – Physical Properties & Identification CLEAVAGE QUALITY – Excellent/perfect Excellent cleavage: smooth breakage surface

# OF CLEAVAGE DIRECTIONS GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS A number Only applies to good or excellent cleavage quality

# OF CLEAVAGE DIRECTIONS - One GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS - One One smooth surface

# OF CLEAVAGE DIRECTIONS - Two GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS - Two Two non-parallel smooth surfaces

# OF CLEAVAGE DIRECTIONS - Three GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS - Three Three non-parallel smooth surfaces

# OF CLEAVAGE DIRECTIONS - Four GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS - Four Fluorite Four non-parallel smooth surfaces

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

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

CRYSTAL HABIT Well-formed crystal faces GEOL 131: Minerals – Physical Properties & Identification CRYSTAL HABIT Well-formed crystal faces Poorly-formed crystals: not enough space

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

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

GEOL 131: Minerals – Physical Properties & Identification HARDNESS

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

Magnetite (Fe3O4) attracting a magnet GEOL 131: Minerals – Physical Properties & Identification MAGNETISM Some iron-rich minerals are magnetic Magnetite (Fe3O4) attracting a magnet

MINERAL IDENTIFICATION GEOL 131: Minerals – Physical Properties & Identification MINERAL IDENTIFICATION Table or flowchart Observation of unique properties Narrow down possibilities

MINERAL IDENTIFICATION GEOL 131: Minerals – Physical Properties & Identification MINERAL IDENTIFICATION

Minerals Atoms & Elements

All Minerals Are Made of Atoms GEOL 131: Minerals – Atoms and Elements All Minerals Are Made of Atoms

GEOL 131: Minerals – Atoms and Elements The Periodic Table of the Elements http://www.ptable.com/

Basic Structure of an Atom GEOL 131: Minerals – Atoms and Elements Basic Structure of an Atom

GEOL 131: Minerals – Atoms and Elements Valence Shells

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

GEOL 131: Minerals – Atoms and Elements Atomic Bonds

GEOL 131: Minerals – Atoms and Elements Atomic Bonds

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

Atomic Structure of Minerals GEOL 131: Minerals – Atoms and Elements Atomic Structure of Minerals Arrangement of atoms Well-ordered: Repeats in a regular pattern

Atomic Structure of Minerals GEOL 131: Minerals – Atoms and Elements Atomic Structure of Minerals Arrangement of atoms QUARTZ

Atomic Structure – Diamond vs Graphite GEOL 131: Minerals – Atoms and Elements Atomic Structure – Diamond vs Graphite

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

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)

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

MINERAL GROUPS - Silicates GEOL 131: Minerals – Mineral Groups MINERAL GROUPS - Silicates Silicate structures

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)

MINERAL GROUPS - Silicates GEOL 131: Minerals – Mineral Groups MINERAL GROUPS - Silicates Example: Hardness 3-D frameworks make harder minerals Quartz

MINERAL GROUPS - Silicates GEOL 131: Minerals – Mineral Groups MINERAL GROUPS - Silicates Example: Cleavage Sheet structures produce sheet cleavage Micas

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)

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

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

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

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

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)

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

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)

End of Minerals chapter