MineralsMinerals

Minerals

What are they?

Uses of …

Identification

Formation of ….

Composition

Classification

Crystal Systems

What is a Mineral?What is a Mineral?

There are five criteria that a There are five criteria that a substance must meet in order to be substance must meet in order to be considered a mineral. To be a considered a mineral. To be a mineral a substance must:mineral a substance must:

1.1. Be naturally occurringBe naturally occurring

2.2. Be inorganicBe inorganic

3.3. Be solid at room temperatureBe solid at room temperature

4.4. Possess a definite chemical compositionPossess a definite chemical composition

5.5. Possess a well defined crystal structurePossess a well defined crystal structure

What is a Mineral?What is a Mineral? Minerals are Minerals are naturally occurringnaturally occurring. Minerals . Minerals

are never man-made. If a substance that is are never man-made. If a substance that is normally found in nature can be normally found in nature can be manufactured. The manufactured material manufactured. The manufactured material is not considered a mineral.is not considered a mineral.

Natural Diamond: Synthetic Diamond:

Mineral Non-Mineral

What is a Mineral?What is a Mineral? Minerals are Minerals are inorganicinorganic substances. This substances. This

means that they did not form as a result of means that they did not form as a result of a biological process.a biological process.

Coal: Not a Mineral Amber: Not a Mineral

Fossilized Plant Remains Fossilized Plant Resins

What is a Mineral?What is a Mineral? Minerals are always Minerals are always solid at room temperaturesolid at room temperature. The . The

majority of metals and non-metals of the periodic table are majority of metals and non-metals of the periodic table are minerals. There are exceptions:minerals. There are exceptions:

The gases: HThe gases: H22, N, N22, O, O22, F, F22, Cl, Cl22, and the Noble Gases, and the Noble Gases The metal Mercury (Hg) and the non-metal Bromine (BrThe metal Mercury (Hg) and the non-metal Bromine (Br22))

Hg Br2

What is a Mineral?What is a Mineral?

Minerals have Minerals have definite chemical definite chemical compositionscompositions..

Minerals are pure substances meaning Minerals are pure substances meaning they are either compounds, or elements.they are either compounds, or elements.

Minerals are never mixturesMinerals are never mixtures

Native Copper

What is a Mineral?What is a Mineral? Minerals have Minerals have well defined crystal well defined crystal

structuresstructures..

Classification of MineralsClassification of Minerals

Minerals are classified according to Minerals are classified according to the following criteria:the following criteria:

Chemical Composition (eight classes)Chemical Composition (eight classes)Crystal System (six systems)Crystal System (six systems)Method of Formation (three methods)Method of Formation (three methods)

Chemical CompositionChemical Composition

•Native ElementsNative Elements•SilicatesSilicates•CarbonatesCarbonates•HalidesHalides•OxidesOxides•HydroxidesHydroxides•SulfidesSulfides•SulfatesSulfates

Chemical Composition: Native ElementsChemical Composition: Native Elements

Elements that can be found in a pure state Elements that can be found in a pure state Common native elements include gold, silver, Common native elements include gold, silver,

and copperand copper

Gold (Au)

Copper (Cu)

Chemical Composition: SilicatesChemical Composition: Silicates

The largest chemical The largest chemical class of minerals. class of minerals.

Silicates are so Silicates are so prevalent because the prevalent because the silicate structure silicate structure comes in many forms.comes in many forms.

These forms include: These forms include: individual tetrahedra, individual tetrahedra, single chains, double single chains, double chains, sheets, and chains, sheets, and network solidsnetwork solids

Common minerals Common minerals include: Olivine, include: Olivine, Orthoclase and Orthoclase and plagioclase Feldspars, plagioclase Feldspars, and Quartzand Quartz

Silica Tetrahedron

Single Chain

Double Chain

Sheet / Network Solids

Chemical Composition: CarbonatesChemical Composition: Carbonates

Carbonates include all minerals that include the COCarbonates include all minerals that include the CO33-2-2 anion. anion.

Common carbonates include Calcite (CaCOCommon carbonates include Calcite (CaCO33) and Dolomite (MgCO) and Dolomite (MgCO33)) Calcite is the mineral that comprises limestoneCalcite is the mineral that comprises limestone

Chemical Composition: HalidesChemical Composition: Halides

Halides are minerals that contain anions from the halogen Halides are minerals that contain anions from the halogen ((Gr. “Salt Forming”Gr. “Salt Forming”) family of the periodic table.) family of the periodic table.

Halides will have FHalides will have F--, Cl, Cl--, Br, Br--, I, I--, anions as part of their , anions as part of their chemical compositionchemical composition

Among the most common halides are halite (NaCl) and Among the most common halides are halite (NaCl) and Fluorite (CaFFluorite (CaF22))

Chemical Composition: Oxides and Chemical Composition: Oxides and HydroxidesHydroxides

Oxides include all minerals that contain Oxides include all minerals that contain the Othe O-2-2 anion. anion.

Hydroxides contain the OHHydroxides contain the OH-- anion anion Common Oxides include Hematite and Common Oxides include Hematite and

Magnetite (both are iron oxides)Magnetite (both are iron oxides)

Chemical Composition: SulfidesChemical Composition: Sulfides

Sulfides include all minerals that contain Sulfides include all minerals that contain the Sthe S-2-2 anion anion

Common Sulfides include Galena (PbS) Common Sulfides include Galena (PbS) and Pyrite (FeS)and Pyrite (FeS)

Chemical Composition: SulfatesChemical Composition: Sulfates

Sulfates include all minerals that include Sulfates include all minerals that include the SOthe SO44

-2-2 polyatomic anion. polyatomic anion.

Common sulfates include Gypsum (CaSOCommon sulfates include Gypsum (CaSO44) ) and Epsomite (MgSOand Epsomite (MgSO44))

Crystal SystemsCrystal Systems

CubicCubicTetragonalTetragonalOrthorhombicOrthorhombicHexagonalHexagonalMonoclinicMonoclinicTriclinicTriclinic

Crystal System: Cubic or IsometricCrystal System: Cubic or Isometric

Crystal System: TetragonalCrystal System: Tetragonal

Crystal System: OrthorhombicCrystal System: Orthorhombic

Crystal System: HexagonalCrystal System: Hexagonal

Crystal System: MonoclinicCrystal System: Monoclinic

Crystal System: TriclinicCrystal System: Triclinic

Methods of FormationMethods of Formation

IgneousIgneousMetamorphicMetamorphicChemicalChemical

Method of Formation: Igneous MineralsMethod of Formation: Igneous Minerals

Igneous minerals are those minerals which form from the cooling and solidification of magmas (inside the Earth) and lavas (on the surface of the Earth).

Quartz Mica Feldspar Olivine

Method of Formation: Metamorphic MineralsMethod of Formation: Metamorphic Minerals

Metamorphic minerals are those that form Metamorphic minerals are those that form from pre-existing minerals that have been from pre-existing minerals that have been exposed to high temperature and or exposed to high temperature and or pressure.pressure.

Staurolite Dioptase Grossular Spessartite

Chemical Formation: EvaporitesChemical Formation: Evaporites

• EvaporiteEvaporite minerals form as the water that minerals form as the water that minerals are dissolved in evaporates. minerals are dissolved in evaporates. • Evaporation increases the concentration of a Evaporation increases the concentration of a mineral until the solution is saturated. mineral until the solution is saturated. • Any further evaporation will result in the Any further evaporation will result in the formation of mineral crystals.formation of mineral crystals.

Halite – NaCl

The blue is the result of trace elements

Chemical Formation: PrecipitatesChemical Formation: Precipitates

• PrecipitatePrecipitate minerals form when the concentration of ions in minerals form when the concentration of ions in solution increases to the point that insoluble salts form and solution increases to the point that insoluble salts form and sink to the bottom of the body of water in which it forms.sink to the bottom of the body of water in which it forms.

• PrecipitatesPrecipitates often form in lagoons and in lakes that dry out often form in lagoons and in lakes that dry out due to rapid evaporation, or when calcium rich fresh water due to rapid evaporation, or when calcium rich fresh water pours into ocean water with a significant amount of pours into ocean water with a significant amount of dissolved COdissolved CO22

Calcite – CaCO3Dolomite – CaMg(CO3)2

How are Minerals Identified?How are Minerals Identified?

Minerals are identified using several Minerals are identified using several physical properties. Among the physical properties. Among the physical properties used are:physical properties used are:

Color Color CleavageCleavage

Hardness Hardness FractureFracture

Streak Streak Unique - PropertiesUnique - Properties

LusterLuster

ColorColor

Color is the least useful of all identifiable Color is the least useful of all identifiable characteristics of mineralscharacteristics of minerals

The same mineral may come in many The same mineral may come in many color varieties due to the presence of trace color varieties due to the presence of trace elements. Ex. elements. Ex. quartz

Many different minerals may appear to be Many different minerals may appear to be the same color Ex. the same color Ex. gold and pyrite

HardnessHardness

Hardness is the Hardness is the resistance that a resistance that a mineral has to mineral has to being scratched by being scratched by another mineral.another mineral.

Mohs Scale of Hardness is used to is used to determine the determine the hardness of a hardness of a mineral sample mineral sample

StreakStreak Streak is the determination of the true color of a Streak is the determination of the true color of a

mineral by looking at a powdered sample of the mineral by looking at a powdered sample of the mineral.mineral.

Minerals are powdered by rubbing them against Minerals are powdered by rubbing them against a piece of unglazed porcelain plate.a piece of unglazed porcelain plate.

Powdering the mineral eliminates the influence Powdering the mineral eliminates the influence of trace elementsof trace elements

This is most useful for minerals softer than Mohs This is most useful for minerals softer than Mohs 77

LusterLuster Luster is the quality of Luster is the quality of

the light reflected the light reflected from the surface of a from the surface of a mineral.mineral.

There are over thirty There are over thirty categories of luster categories of luster and it takes an expert and it takes an expert to differentiate them to differentiate them allall

In this course we will In this course we will only classify minerals only classify minerals as having a metallic, as having a metallic, non-metallic, or glassy non-metallic, or glassy luster. luster.

CleavageCleavage Cleavage occurs when minerals split along flat, smooth Cleavage occurs when minerals split along flat, smooth

surfaces.surfaces. Cleavage occurs because there is a plane of weakness created Cleavage occurs because there is a plane of weakness created

by weak molecular bonds oriented in a particular directionby weak molecular bonds oriented in a particular direction There are six types of cleavage each associated with the There are six types of cleavage each associated with the

number of planes involved and the angle between the number of planes involved and the angle between the cleavage planescleavage planes

FractureFracture Fracture of mineral Fracture of mineral

samples occurs when samples occurs when minerals break along minerals break along uneven, or jagged uneven, or jagged surfaces.surfaces.

Fracture occurs when Fracture occurs when there is no particular there is no particular orientation to the orientation to the weak bonds in a weak bonds in a mineral, or when all mineral, or when all bonds are of equal bonds are of equal strengthstrength

There are six types of There are six types of fracturefracture

Special PropertiesSpecial Properties

Magnetism ex. magnetiteMagnetism ex. magnetite Taste ex. haliteTaste ex. halite Oder ex. sulfur and pyriteOder ex. sulfur and pyrite Phosphorescence ex. calcitePhosphorescence ex. calcite Fluorescence ex. calciteFluorescence ex. calcite Specific Gravity ex. all mineralsSpecific Gravity ex. all minerals Reaction with Acids/Bases ex. calciteReaction with Acids/Bases ex. calcite Birefringence ex. calciteBirefringence ex. calcite

Uses of MineralsUses of Minerals

The two primary uses of minerals are:The two primary uses of minerals are:

Commercially and Strategically Commercially and Strategically

Valuable OresValuable Ores

Gemstones Gemstones

What is an Ore?What is an Ore?

An ore is a mineral that can be mined and An ore is a mineral that can be mined and refined to extract a commercially or refined to extract a commercially or strategically valuable substancestrategically valuable substance

Examples of important ores are: Examples of important ores are: hematite and magnetite (iron ores)hematite and magnetite (iron ores)galena (lead ore)galena (lead ore)sphalerite (zinc ore)sphalerite (zinc ore)bauxite (aluminum ore)bauxite (aluminum ore)

GemstonesGemstones

To qualify as a gemstone a mineral To qualify as a gemstone a mineral must be:must be:

Rare – increases monetary valueRare – increases monetary valueDurable – increases longevityDurable – increases longevityBeautiful – increases demandBeautiful – increases demand

Varieties of Quartz

Different Minerals with the Same Color

Mohs Scale of Hardness