Chapter 1. Minerals. Formation of Minerals Minerals form when atoms of elements combine through chemical bonding Minerals form when atoms of elements.

Chapter 1. MineralsChapter 1. Minerals

Formation of MineralsFormation of Minerals

Minerals form when atoms of elements combine Minerals form when atoms of elements combine through chemical bondingthrough chemical bonding

• Formation of Sodium ChlorideFormation of Sodium Chloride SodiumSodium: soft, silvery metal; : soft, silvery metal; ChorineChorine: green, : green,

poisonous gaspoisonous gas Sodium atom loses one electron and chlorine atom Sodium atom loses one electron and chlorine atom

gains one electron while forming sodium chloride gains one electron while forming sodium chloride

Periodic TablePeriodic Table

Formation of Minerals cont’d..Formation of Minerals cont’d..

AtomAtom Atomic NumberAtomic Number IonsIons Ionic bondingIonic bonding Covalent bonding Covalent bonding Atomic mass or Mass Number Atomic mass or Mass Number Isotopes Isotopes Radioactive DecayRadioactive Decay

Formation of Minerals cont’d..Formation of Minerals cont’d..

AtomAtom• Atom Atom is characterized by a relatively small nucleus of tightly packed is characterized by a relatively small nucleus of tightly packed

protons and neutrons with a surrounding cloud of electronsprotons and neutrons with a surrounding cloud of electrons

Atomic NumberAtomic Number• Number of Protons (or number of electrons)Number of Protons (or number of electrons)

IonsIons• Electrically charged atomsElectrically charged atoms

Ionic bondingIonic bonding• electron transferelectron transfer

Covalent bondingCovalent bonding• electron sharingelectron sharing

Atomic mass or Mass NumberAtomic mass or Mass Number• Number of Protons + Number of NeutronsNumber of Protons + Number of Neutrons

Formation of Minerals cont’d..Formation of Minerals cont’d..

Isotopes:Isotopes:

• Atoms of the same element with similar number of Atoms of the same element with similar number of protons but different number of neutronsprotons but different number of neutrons

Radioactive DecayRadioactive Decay

• The process of disintegration of isotopes with unstable The process of disintegration of isotopes with unstable nuclei nuclei

• Occurs when the forces that bind the nucleus are not Occurs when the forces that bind the nucleus are not strong enough to keep it togetherstrong enough to keep it together

• Associated with the radiation of energy and particlesAssociated with the radiation of energy and particles

Characteristics of MineralsCharacteristics of Minerals

Natural Inorganic (never alive) SolidsNatural Inorganic (never alive) Solids

Characteristics of Minerals cont’d..Characteristics of Minerals cont’d..

Internal StructureInternal Structure

Characteristics of Minerals cont’d..Characteristics of Minerals cont’d..

Composition of mineralsComposition of minerals• Minerals have definite chemical Minerals have definite chemical

composition, in which specific composition, in which specific elements occur in definite elements occur in definite proportionsproportions

The Growth of MineralsThe Growth of Minerals

• Crystal GrowthCrystal Growth Accomplished by crystallization during which atoms Accomplished by crystallization during which atoms

are added to a crystal faceare added to a crystal face

• Environment suitable for crystal growthEnvironment suitable for crystal growth Proper concentration of the kinds of atoms or ions Proper concentration of the kinds of atoms or ions

required for a particular mineralrequired for a particular mineral Proper temperature and pressureProper temperature and pressure

Physical PropertiesPhysical PropertiesProperties used to identify mineralsProperties used to identify minerals

• StreakStreak• CleavageCleavage• FractureFracture• HardnessHardness• LusterLuster • Specific gravitySpecific gravity• Other propertiesOther properties

Physical PropertiesPhysical Properties Properties used to identify mineralsProperties used to identify minerals

• StreakStreak Color of the mineral in its powder formColor of the mineral in its powder form

• CleavageCleavage The tendency of a mineral to break along planes of The tendency of a mineral to break along planes of

weak bondingweak bonding Types of cleavage: basal or sheet (1 direction); Types of cleavage: basal or sheet (1 direction);

prismatic (2 directions); cubic (3 directions at right prismatic (2 directions); cubic (3 directions at right angles); rhombohedral (3 directions not at right angles); rhombohedral (3 directions not at right angles); octahedral (4 directions); dodecahedral (6 angles); octahedral (4 directions); dodecahedral (6 directions)directions)

Properties used to identify mineralsProperties used to identify minerals

• FractureFracture Describes the Breakage of mineral, not Describes the Breakage of mineral, not

along cleavage planesalong cleavage planes • HardnessHardness

Measure of mineral’s resistance to abrasionMeasure of mineral’s resistance to abrasion Moh’s Hardness Scale: 1-10Moh’s Hardness Scale: 1-10

Samples of Samples of Minerals Minerals on Moh’s on Moh’s Hardness Hardness

ScaleScale

1. Talc1. Talc 2. Gypsum2. Gypsum

3. Calcite3. Calcite

4. Fluorite4. Fluorite

5. Apatite5. Apatite

6. K-feldspar6. K-feldspar

7. Quartz7. Quartz

8. Topaz8. Topaz

9. Corundum9. Corundum10. Diamond10. Diamond

Physical Properties cont’d..Physical Properties cont’d..

• LusterLuster Quality and intensity of light that is Quality and intensity of light that is

reflected from the surface of a mineral reflected from the surface of a mineral

Few Examples of LusterFew Examples of Luster• Vitreous - the most common luster, it simply means the look Vitreous - the most common luster, it simply means the look

of glassof glass• Metallic - the look of metals Metallic - the look of metals • Adamantine - very gemmy crystals Adamantine - very gemmy crystals • Pearly - the look of a pearl Pearly - the look of a pearl • Resinous - the look of resins such as dried glue or chewing Resinous - the look of resins such as dried glue or chewing

gum gum • Silky - the look of silk, similar to fibrous but more compact Silky - the look of silk, similar to fibrous but more compact

Physical Properties cont’d..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 Magnetism, reaction to acid, taste, feel (soapy or

greasy)greasy)

Abundance of elements in the Abundance of elements in the Continental CrustContinental Crust

Rock-forming MineralsRock-forming Minerals

• Most abundant few dozen mineralsMost abundant few dozen minerals

Types of Rock-forming MineralsTypes of Rock-forming Minerals

• SilicatesSilicates

A group of minerals containing atoms A group of minerals containing atoms of silicon and oxygen linked in of silicon and oxygen linked in tetrahedral units called silica tetrahedral units called silica tetrahedronstetrahedrons

• Non-silicatesNon-silicates

Minerals other than silicate mineralsMinerals other than silicate minerals carbonates, oxides, sulfides, sulfates, carbonates, oxides, sulfides, sulfates,

halides, native elements halides, native elements

Silicate MineralsSilicate Minerals

Most of earth’s crust (more than 95 %) and mantle Most of earth’s crust (more than 95 %) and mantle are made of silicate mineralsare made of silicate minerals

A group of minerals containing atoms of silicon A group of minerals containing atoms of silicon and oxygen linked in tetrahedral units called silica and oxygen linked in tetrahedral units called silica tetrahedronstetrahedrons

Silica Tetrahedron = 1 Silicon & 4 Oxygen atoms Silica Tetrahedron = 1 Silicon & 4 Oxygen atoms

Silicate MineralsSilicate Minerals

Common elements such as Fe, Mg, Na, Ca, K and Al Common elements such as Fe, Mg, Na, Ca, K and Al combine with Si and Ocombine with Si and O22 to make silicate minerals to make silicate minerals

Characterized by different types of silicate Characterized by different types of silicate structures structures

Silicate Structures Silicate Structures

• Defined by the configuration of Defined by the configuration of silicon-oxygen tetrahedrons in the silicon-oxygen tetrahedrons in the silicate mineralssilicate minerals

Silicate Minerals cont’d…Silicate Minerals cont’d…

SILICATE STRUCTURESILICATE STRUCTURE MINERAL NAMESMINERAL NAMES

IsolatedIsolated OlivineOlivine

Single ChainSingle Chain PyroxenePyroxene

Double ChainDouble Chain AmphiboleAmphibole

SheetSheet Micas, Clays, ChloriteMicas, Clays, Chlorite

3-D Network3-D Network Quartz, K-Feldspar, Quartz, K-Feldspar, Plagioclase FeldsparPlagioclase Feldspar

Minerals other than silicate mineralsMinerals other than silicate minerals Most of these are carbonates or sulfatesMost of these are carbonates or sulfates Typically form at low temperatures and Typically form at low temperatures and

pressures near earth’s surfacepressures near earth’s surface ExamplesExamples

• Calcite, Dolomite, Halite, Gypsum, Calcite, Dolomite, Halite, Gypsum, Pyrite, Galena, MagnetitePyrite, Galena, Magnetite

Non-silicate MineralsNon-silicate Minerals

Minerals of Economic valueMinerals 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…Non-silicate Minerals cont’d…