Chapter 1. Minerals

Formation of Minerals Minerals form when atoms of elements combine through chemical bonding Minerals form when atoms of elements combine through chemical bonding Formation of Sodium ChlorideFormation of Sodium Chloride Sodium: soft, silvery metal; Chorine: green, poisonous gas Sodium: soft, silvery metal; Chorine: green, poisonous gas Sodium atom loses one electron and chlorine atom gains one electron while forming sodium chloride Sodium atom loses one electron and chlorine atom gains one electron while forming sodium chloride

Periodic Table

Formation of Minerals cont’d.. Atom Atom Atomic Number Atomic Number Ions Ions Ionic bonding Ionic bonding Covalent bonding Covalent bonding Atomic mass or Mass Number Atomic mass or Mass Number Isotopes Isotopes Radioactive Decay Radioactive Decay

Formation of Minerals cont’d.. Atom Atom Atom is characterized by a relatively small nucleus of tightly packed protons and neutrons with a surrounding cloud of electronsAtom is characterized by a relatively small nucleus of tightly packed protons and neutrons with a surrounding cloud of electrons Atomic Number Atomic Number Number of Protons (or number of electrons)Number of Protons (or number of electrons) Ions Ions Electrically charged atomsElectrically charged atoms Ionic bonding Ionic bonding electron transferelectron transfer Covalent bonding Covalent bonding electron sharingelectron sharing Atomic mass or Mass Number Atomic mass or Mass Number Number of Protons + Number of NeutronsNumber of Protons + Number of Neutrons

Formation of Minerals cont’d.. Isotopes: Isotopes: Atoms of the same element with similar number of protons but different number of neutronsAtoms of the same element with similar number of protons but different number of neutrons Radioactive Decay Radioactive Decay The process of disintegration of isotopes with unstable nucleiThe process of disintegration of isotopes with unstable nuclei Occurs when the forces that bind the nucleus are not strong enough to keep it togetherOccurs when the forces that bind the nucleus are not strong enough to keep it together Associated with the radiation of energy and particlesAssociated with the radiation of energy and particles

Characteristics of Minerals Natural Inorganic (never alive) Solids Natural Inorganic (never alive) Solids

Characteristics of Minerals cont’d.. Internal Structure Internal Structure

Characteristics of Minerals cont’d.. Composition of minerals Composition of minerals Minerals have definite chemical composition, in which specific elements occur in definite proportionsMinerals have definite chemical composition, in which specific elements occur in definite proportions

The Growth of Minerals Crystal GrowthCrystal Growth Accomplished by crystallization during which atoms are added to a crystal face Accomplished by crystallization during which atoms are added to a crystal face Environment suitable for crystal growthEnvironment suitable for crystal growth Proper concentration of the kinds of atoms or ions required for a particular mineral Proper concentration of the kinds of atoms or ions required for a particular mineral Proper temperature and pressure Proper temperature and pressure

Physical Properties Properties used to identify minerals StreakStreak CleavageCleavage FractureFracture HardnessHardness LusterLuster Specific gravitySpecific gravity Other propertiesOther properties

Physical Properties Properties used to identify minerals Properties used to identify minerals StreakStreak Color of the mineral in its powder form Color of the mineral in its powder form CleavageCleavage The tendency of a mineral to break along planes of weak bonding The tendency of a mineral to break along planes of weak bonding Types of cleavage: basal or sheet (1 direction); prismatic (2 directions); cubic (3 directions at right angles); rhombohedral (3 directions not at right angles); octahedral (4 directions); dodecahedral (6 directions) Types of cleavage: basal or sheet (1 direction); prismatic (2 directions); cubic (3 directions at right angles); rhombohedral (3 directions not at right angles); octahedral (4 directions); dodecahedral (6 directions)

Properties used to identify minerals FractureFracture Describes the Breakage of mineral, not along cleavage planes Describes the Breakage of mineral, not along cleavage planes HardnessHardness Measure of mineral’s resistance to abrasion Measure of mineral’s resistance to abrasion Moh’s Hardness Scale: 1-10 Moh’s Hardness Scale: 1-10

Samples of Minerals on Moh’s Hardness Scale 1. Talc 2. Gypsum 3. Calcite 4. Fluorite 5. Apatite 6. K-feldspar 7. Quartz 8. Topaz 9. Corundum 10. Diamond

Physical Properties cont’d.. LusterLuster Quality and intensity of light that is reflected from the surface of a mineral Quality and intensity of light that is reflected from the surface of a mineral Few Examples of Luster Vitreous - the most common luster, it simply means the look of glassVitreous - the most common luster, it simply means the look of glass Metallic - the look of metalsMetallic - the look of metals Adamantine - very gemmy crystalsAdamantine - very gemmy crystals Pearly - the look of a pearlPearly - the look of a pearl Resinous - the look of resins such as dried glue or chewing gumResinous - the look of resins such as dried glue or chewing gum Silky - the look of silk, similar to fibrous but more compactSilky - the look of silk, similar to fibrous but more compact

Physical Properties cont’d.. Specific gravitySpecific gravity Measure of heaviness of a mineral Measure of heaviness of a mineral Low, medium, high Low, medium, high Special propertiesSpecial properties Magnetism, reaction to acid, taste, feel (soapy or greasy) Magnetism, reaction to acid, taste, feel (soapy or greasy)

Abundance of elements in the Continental Crust

Rock-forming Minerals Most abundant few dozen mineralsMost abundant few dozen minerals

Types of Rock-forming Minerals SilicatesSilicates A group of minerals containing atoms of silicon and oxygen linked in tetrahedral units called silica tetrahedrons A group of minerals containing atoms of silicon and oxygen linked in tetrahedral units called silica tetrahedrons Non-silicatesNon-silicates Minerals other than silicate minerals Minerals other than silicate minerals carbonates, oxides, sulfides, sulfates, halides, native elements carbonates, oxides, sulfides, sulfates, halides, native elements

Silicate Minerals Most of earth’s crust (more than 95 %) and mantle are made of silicate minerals Most of earth’s crust (more than 95 %) and mantle are made of silicate minerals A group of minerals containing atoms of silicon and oxygen linked in tetrahedral units called silica tetrahedrons A group of minerals containing atoms of silicon and oxygen linked in tetrahedral units called silica tetrahedrons Silica Tetrahedron = 1 Silicon & 4 Oxygen atoms Silica Tetrahedron = 1 Silicon & 4 Oxygen atoms

Silicate Minerals Common elements such as Fe, Mg, Na, Ca, K and Al combine with Si and O 2 to make silicate minerals Common elements such as Fe, Mg, Na, Ca, K and Al combine with Si and O 2 to make silicate minerals Characterized by different types of silicate structures Characterized by different types of silicate structures

Silicate Structures Silicate Structures Defined by the configuration of silicon-oxygen tetrahedrons in the silicate mineralsDefined by the configuration of silicon-oxygen tetrahedrons in the silicate minerals Silicate Minerals cont’d… SILICATE STRUCTURE MINERAL NAMES IsolatedOlivine Single Chain Pyroxene Double Chain Amphibole Sheet Micas, Clays, Chlorite 3-D Network Quartz, K-Feldspar, Plagioclase Feldspar

Minerals other than silicate minerals Minerals other than silicate minerals Most of these are carbonates or sulfates Most of these are carbonates or sulfates Typically form at low temperatures and pressures near earth’s surface Typically form at low temperatures and pressures near earth’s surface Examples Examples Calcite, Dolomite, Halite, Gypsum, Pyrite, Galena, MagnetiteCalcite, Dolomite, Halite, Gypsum, Pyrite, Galena, Magnetite Non-silicate Minerals

Minerals of Economic value Minerals of Economic value Ores of metals and gemstonesOres of metals and gemstones ExamplesExamples Galena (lead) Galena (lead) Sphalerite (zinc) Sphalerite (zinc) Chalcopyrite (copper) Chalcopyrite (copper) Hematite (iron) Hematite (iron) Diamond (carbon) Diamond (carbon) Emerald (beryl) Emerald (beryl) Ruby and sapphire (corundum) Ruby and sapphire (corundum) Non-silicate Minerals cont’d…