AtomsAtoms

Atoms – basic building blocks for all earth Atoms – basic building blocks for all earth materials; consist of 3 basic components: materials; consist of 3 basic components: protons, neutrons, electronsprotons, neutrons, electrons

Atoms combine to form Atoms combine to form ElementsElements

ElementsElements – fundamental component that – fundamental component that can not be broken down into other can not be broken down into other substances by ordinary chemical substances by ordinary chemical processesprocesses

Elements combine to form mineralsElements combine to form minerals

General Facts About MineralsGeneral Facts About Minerals

2,000 + minerals have been identified2,000 + minerals have been identified

A few are “native elements” -- made of A few are “native elements” -- made of only one element, such as sulfur, gold. only one element, such as sulfur, gold. copper, and graphite (carbon)copper, and graphite (carbon)

Most are compounds, especially the Most are compounds, especially the silicate group (Si, O).silicate group (Si, O).

Other important groups are oxides, Other important groups are oxides, carbonates, and sulfides.carbonates, and sulfides.

Gold (Au)Silver (Ag)Platinum (Pt)Diamond (C)Graphite (C)Sulfur (S)Copper (Cu)

MINERALS

NATIVE ELEMENTS

Copper

Silver

Gold

Mineral CriteriaMineral Criteria

1. Crystalline solid1. Crystalline solid2.2. Naturally occurringNaturally occurring3.3. Have a definite chemical compositionHave a definite chemical composition4. Inorganic4. Inorganic

Minerals are identified by their Minerals are identified by their Physical Properties Physical Properties

Crystal FormCrystal FormColorColorStreakStreakLuster – metallic, non-metallic Luster – metallic, non-metallic Hardness – Moh’s Hardness Scale (1-10)Hardness – Moh’s Hardness Scale (1-10)CleavageCleavageFractureFractureSpecific Gravity Specific Gravity OthersOthers

A mineral’s physical properties A mineral’s physical properties are controlled by its are controlled by its internal internal

arrangement of atomsarrangement of atoms

regularly repeating, orderly patternregularly repeating, orderly pattern

The most common crystalline The most common crystalline structure structure

Silica-oxygen tetrahedronSilica-oxygen tetrahedron – basic – basic building block for silicate mineralsbuilding block for silicate minerals

Silica tetrahedron combine Silica tetrahedron combine several different waysseveral different ways

Five major types of Five major types of silicate minerals silicate minerals based on their based on their structurestructure

A)A) Isolated tetrahedronIsolated tetrahedron

B)B) Single chainSingle chain

C) Double chainsC) Double chains

D) Sheet silicates D) Sheet silicates

E) 3-D framework E) 3-D framework silicatessilicates

Minerals can have the same chemical composition Minerals can have the same chemical composition (Carbon) but different physical properties because (Carbon) but different physical properties because

of their crystal structureof their crystal structure

Diamond GraphiteDiamond Graphite

COLORCOLOR

Color is not usually a definitive property of Color is not usually a definitive property of a mineral. a mineral.

Some minerals have characteristics colorsSome minerals have characteristics colorsOthers vary due to chemical differences or Others vary due to chemical differences or

impurities (atoms mixed inside the main impurities (atoms mixed inside the main elements)elements)

However most minerals have a variety of However most minerals have a variety of colorscolors..

Some Colors of Quartz

STREAKSTREAK

For opaque minerals, if you rub the For opaque minerals, if you rub the sample across a streak plate, it will leave a sample across a streak plate, it will leave a colored powder. This streak is distinctive colored powder. This streak is distinctive for minerals and is used to identify for minerals and is used to identify minerals. minerals.

Varieties of Hematite – all same color streak

HARDNESS – Mineral’s resistance to HARDNESS – Mineral’s resistance to scratching. Minerals with higher numbers scratching. Minerals with higher numbers

will scratch minerals belowwill scratch minerals below

LUSTERLUSTER

Describes how light reflects off the surface Describes how light reflects off the surface

Categories: Metallic or non-metallicCategories: Metallic or non-metallic

Metallic does not mean shinyMetallic does not mean shiny

Non-metallic: vitreous or glassy; silky; Non-metallic: vitreous or glassy; silky; resinous; pearly; greasy; waxy, dull; earthyresinous; pearly; greasy; waxy, dull; earthy

Examples of metallic lusterExamples of metallic luster

Pyrite (FeS2)Galena (PbS)

More Examples of Metallic Luster

PYRITE

GALENA

Example of non-metallic lusterExample of non-metallic luster

Vitreous--quartzVitreous--quartz

Example of non-metallic lusterExample of non-metallic luster

Silky--example plagioclase feldsparSilky--example plagioclase feldspar

Non-metallic and metallic luster – Non-metallic and metallic luster – earthy hematite – metallic hematiteearthy hematite – metallic hematite

Cleavage and FractureCleavage and Fracture

Some minerals split along flat surfaces Some minerals split along flat surfaces when struck hard--this is called mineral when struck hard--this is called mineral cleavagecleavage

Other minerals break unevenly along Other minerals break unevenly along rough or curved surfaces--this is called rough or curved surfaces--this is called fracture fracture

A few minerals have both cleavage and A few minerals have both cleavage and fracture ( mica )fracture ( mica )

Cleavage

FLUORITE

HALITE

Halite (NaCl)Fluorite (CaF2)

Cleavage

BIOTITEMUSCOVITE

Rose Quartz – Conchoidal FractureRose Quartz – Conchoidal Fracture

Conchoidal Fracture - Quartz

Obsidian

DENSITY / SPECIFIC GRAVITY DENSITY / SPECIFIC GRAVITY

This is the ratio of the density of the This is the ratio of the density of the mineral to the density of water. mineral to the density of water.

Weight Air/(Weight Air-Weight in water) = Weight Air/(Weight Air-Weight in water) = specific gravityspecific gravity

Acid Test for CarbonatesAcid Test for Carbonates

Special Characteristics:Special Characteristics:

Carbonates react with dilute HCl and other Carbonates react with dilute HCl and other acids by fizzing or bubbling (releasing acids by fizzing or bubbling (releasing CO2 gas)CO2 gas)

MINERALSNONSILICATE MINERALSCARBONATES

Carbonate ion (CO32-) is prominent in minerals.

Has -2 charge.Combines readily with positive ions.Bonds generally weak.Minerals are soft (3-4).Minerals are soluble in acidic water.

Leads to cave development.

Calcite (CaCO3)Dolomite (CaMg(CO3)2)

DOLOMITE

CALCITE

Less than a dozen are common in Less than a dozen are common in most rocksmost rocks

QuartzQuartz Feldspar (group)Feldspar (group) Muscovite (silver white mica)Muscovite (silver white mica) Biotite (black mica)Biotite (black mica) CalciteCalcite PyroxenePyroxene OlivineOlivine Amphibole (group)Amphibole (group) Magnetite, limonite, and other iron oxidesMagnetite, limonite, and other iron oxides PyritePyrite

Common uses include:Common uses include:

Aluminum--packaging, transport, buildingAluminum--packaging, transport, building Beryllium--gemstones, fluorescent lightsBeryllium--gemstones, fluorescent lights Copper--electric cables, wires, switchesCopper--electric cables, wires, switches Feldspar--glass and ceramicsFeldspar--glass and ceramics Iron--buildings, automobiles, magnetsIron--buildings, automobiles, magnets Calcite--toothpaste, constructionCalcite--toothpaste, construction