Atoms to MineralsAtoms to Minerals

MatterAnd

AtomsChapter 5 section 1

What is matter?What is matter?

Matter is anything that has mass and Matter is anything that has mass and volume.volume.Mass-the amount of material in a substanceMass-the amount of material in a substanceVolume-the amount of space taken up by an Volume-the amount of space taken up by an

object or substance.object or substance.Minerals are made of matter because they Minerals are made of matter because they

have mass and volume.have mass and volume.

What makes up matter?What makes up matter?

Matter is composed of elements.Matter is composed of elements.Element = a substance that cannot be broken into Element = a substance that cannot be broken into

simpler substances by ordinary chemical means.simpler substances by ordinary chemical means.Ex. oxygen, carbon, nitrogen, hydrogen, silicon, goldEx. oxygen, carbon, nitrogen, hydrogen, silicon, goldRepresented by a symbol (as well as name)Represented by a symbol (as well as name)

Elements are made of atomsElements are made of atomsAtoms are the smallest part of an element that has all Atoms are the smallest part of an element that has all

the element’s propertiesthe element’s properties

Structure of an AtomStructure of an Atom Central region called the nucleusCentral region called the nucleus

Consists of protons (positive charges) and Consists of protons (positive charges) and neutrons (neutral/no charge)neutrons (neutral/no charge)

Most of the mass of an atomMost of the mass of an atom ElectronsElectrons

Negatively charged particles that orbit around the Negatively charged particles that orbit around the nucleusnucleus

Located in discrete energy levels called shellsLocated in discrete energy levels called shellsOften called an electron “cloud”Often called an electron “cloud”

In its neutral state, an atom has an equal In its neutral state, an atom has an equal number of protons and electrons…so, it has no number of protons and electrons…so, it has no charge.charge.

An AtomAn AtomAtoms consist mostly of empty space (between the nucleus & its surrounding electrons).

Flattened structure of an atomFlattened structure of an atom# protons (+) equals # electrons (-) Electrons in shells Number of outermost electrons determine types of bonding

ArgonOutermost (Valence) shell

Some definitions:Some definitions:• Atomic number: Atomic number:

number of protons in number of protons in the nucleus (= to the # the nucleus (= to the # of electrons in the of electrons in the atom)atom)

• Atomic Mass: Atomic Mass: total mass of protons and neutrons within an atom’s nucleusThe # of protons and electrons in an

atom determines its properties.

Electrons and Energy LevelsElectrons and Energy Levels

As the # of electrons in atoms increases, As the # of electrons in atoms increases, more energy levels are needed to hold more energy levels are needed to hold them.them.greatest # of energy levels = 7greatest # of energy levels = 7

Each level can hold only a specific number of Each level can hold only a specific number of electrons.electrons.

Classifying AtomsClassifying Atoms

The periodic table is a tool used to The periodic table is a tool used to organize information about the elements.organize information about the elements. In rows from left to right # of protons In rows from left to right # of protons

increasesincreases In vertical (up and down) columns, also called In vertical (up and down) columns, also called

groups, elements have similar chemical groups, elements have similar chemical properties.properties.

Periodic Table of the Elements

Shows atomic number (# protons) and atomic mass (# protons + neutrons). Column shows # electrons in outermost shell

IsotopesIsotopes

The identity of an atom depends on the # The identity of an atom depends on the # of protons.of protons.

Elements that have the same # of protons, Elements that have the same # of protons, but a different # of neutrons (and therefore but a different # of neutrons (and therefore different masses) are called isotopesdifferent masses) are called isotopesMass # of isotope is equal to the # of protons Mass # of isotope is equal to the # of protons

plus the # of neutrons (mass # = #p + #n)plus the # of neutrons (mass # = #p + #n)Often used in geologic dating.Often used in geologic dating.

Bonding of AtomsBonding of Atoms

Most substances on Earth are not pure Most substances on Earth are not pure elements, but rather compounds.elements, but rather compounds.Compounds contain 2 or more elements that Compounds contain 2 or more elements that

are chemically combinedare chemically combinedAtoms are most stable when their Atoms are most stable when their

outermost energy levels are filled (with outermost energy levels are filled (with electrons)electrons)Stable atoms do not readily combine with Stable atoms do not readily combine with

other elements to form compoundsother elements to form compounds

Bonding of AtomsBonding of AtomsAtoms (with shells that are not full) Atoms (with shells that are not full)

try to fill their outermost shell by try to fill their outermost shell by gaining, losing, or sharing electrons.gaining, losing, or sharing electrons.This forms a chemical bond that hold This forms a chemical bond that hold

atoms together.atoms together.3 main bond types:3 main bond types:

1. covalent1. covalent2. ionic2. ionic3. metallic3. metallic

Covalent BondsCovalent Bonds

Some compounds Some compounds form when atoms form when atoms share electrons.share electrons.

Two or more atoms Two or more atoms held together by held together by covalent bonds form covalent bonds form a molecule.a molecule.

Ionic BondsIonic Bonds Other compounds are held Other compounds are held

together by the force of together by the force of electrical attraction between electrical attraction between atoms that have lost or atoms that have lost or gained electrons.gained electrons. loses electron loses electron positive positive

charge.charge. gains an electron gains an electron negative negative

charge.charge. charged atom is called an ioncharged atom is called an ion Ions with opposite charges Ions with opposite charges

attract, forming compounds attract, forming compounds with ionic bonds.with ionic bonds.

Common in many mineralsCommon in many minerals

Metals and NonmetalsMetals and Nonmetals

Metal = element that loses electrons easily to form Metal = element that loses electrons easily to form positive ionspositive ions Ex. sodium, potassium, gold (much of periodic table)Ex. sodium, potassium, gold (much of periodic table) Ionic bonds don’t form between metalsIonic bonds don’t form between metals

Non-metal = element that gains electrons easily to Non-metal = element that gains electrons easily to form negative ionsform negative ions Ex. chlorine, oxygen, nitrogen (right side of periodic table)Ex. chlorine, oxygen, nitrogen (right side of periodic table) Ionic bonds can form between non-metalsIonic bonds can form between non-metals

Bonds form easily between metals and nonmetalsBonds form easily between metals and nonmetals

Metallic BondsMetallic Bonds Formed between metal Formed between metal

atomsatoms

Different Different characteristics than characteristics than bonds that form bonds that form between metal and between metal and nonmetal atomsnonmetal atoms

Electrons move freely Electrons move freely around metal ionsaround metal ions

Compounds and MixturesCompounds and Mixtures CompoundsCompounds

Can have properties unlike those of the elements from Can have properties unlike those of the elements from which it is madewhich it is made

Elements combine in a fixed proportionElements combine in a fixed proportion Can only be separated by chemical means (electricity)Can only be separated by chemical means (electricity)

Ex. waterEx. water hydrogen, and oxygen hydrogen, and oxygenEx. saltEx. salt sodium, and chlorine sodium, and chlorine

MixturesMixtures Individual elements (or compounds) keep their own Individual elements (or compounds) keep their own

propertiesproperties Elements/compounds can be present in any proportionElements/compounds can be present in any proportion Most can be separated by physical means (evaporation)Most can be separated by physical means (evaporation)

Ex. salt waterEx. salt water

Composition Composition and Structure and Structure

of Mineralsof MineralsChapter 5 Section 2

……a naturally occurring,a naturally occurring,

solid,solid,

inorganic substanceinorganic substance

that has a definitethat has a definite

chemical composition & molecular structurechemical composition & molecular structure

What is a mineral?What is a mineral?

Mineral Mineral CriteriaCriteria

The 5 “must haves” to The 5 “must haves” to be classified a MINERALbe classified a MINERAL

1. Naturally 1. Naturally OccurringOccurring

A mineral cannot A mineral cannot be man-made!!!be man-made!!!

It must be formed It must be formed in nature.in nature.

2. Solid Matter2. Solid MatterA mineralA mineral MUST BE A SOLIDMUST BE A SOLID (not (not

a liquid or a gas)!a liquid or a gas)!Minerals Minerals cancan be crushed into be crushed into

powder, which is still a solid!powder, which is still a solid!

3. Definite Chemical 3. Definite Chemical CompositionComposition

Each mineral has a chemical Each mineral has a chemical composition – a “Recipe” for composition – a “Recipe” for making that mineral. Change the making that mineral. Change the recipe and you change the recipe and you change the mineral!mineral!

4. Atoms Arranged in 4. Atoms Arranged in an Orderly Patternan Orderly Pattern

When the atoms When the atoms combine, they must combine, they must form a PATTERN form a PATTERN (crystalline (crystalline structure)structure)

5. INORGANIC5. INORGANIC

A mineral A mineral CANNOTCANNOT be made from be made from anything that is, was, or will be anything that is, was, or will be

living!living!

Shells are PRODUCED by living things Shells are PRODUCED by living things (but the shells themselves are not alive).(but the shells themselves are not alive).

Most minerals are compoundsMost minerals are compounds(elements combine in a fixed proportion).(elements combine in a fixed proportion).

QuartzQuartzCompound of silicon and oxygenCompound of silicon and oxygen

GalenaGalenaCompound of lead and sulfurCompound of lead and sulfur

Minerals made of single elements are Minerals made of single elements are called native elements.called native elements.Silver, copper, sulfur, diamond, graphiteSilver, copper, sulfur, diamond, graphite

Common Mineral Forming Common Mineral Forming Elements Found in Earth’s CrustElements Found in Earth’s Crust

(by mass)

How do minerals form?How do minerals form?1. Solidification1. Solidification of molten materials of molten materials

*atoms, molecules, & ions move closer *atoms, molecules, & ions move closer together & form compoundstogether & form compounds

*minerals that form depend on the types & *minerals that form depend on the types & amounts of elements presentamounts of elements present

*rate of cooling affects size of mineral grains*rate of cooling affects size of mineral grains

2.2. EvaporationEvaporation of seawater of seawater*as water molecules evaporate, dissolved *as water molecules evaporate, dissolved ions bond to form minerals (ex. halite)ions bond to form minerals (ex. halite)

3.3. Transformation Transformation by heat, pressure, or by heat, pressure, or chemical actionchemical action

Structure of Minerals: Structure of Minerals: Crystal StructureCrystal Structure

All minerals have All minerals have CRYSTALLINE STRUCTUrE (internal arrangement of atoms)**The internal arrangement of atoms

affects the mineral’s physical properties, especially shape, hardness and cleavage/fracture.**

repeated in three dimensionsrepeated in three dimensionshalite

Crystal FacesCrystal FacesSome minerals actually form Some minerals actually form

“crystals” (a regular geometric “crystals” (a regular geometric solid with smooth surfaces called solid with smooth surfaces called crystal faces)crystal faces)

However, there may not be enough However, there may not be enough room for crystal faces to develop fully, room for crystal faces to develop fully, or “grow.” The mineral just fills the or “grow.” The mineral just fills the available space.available space.

The mineral is still crystalline, but crystal The mineral is still crystalline, but crystal faces are not visible.faces are not visible.

Systems

Examples

6 Basic Crystal Shapes6 Basic Crystal ShapesThe angle between crystal faces is characteristic foreach type of mineral and can be used in identification.

SilicatesSilicon Oxygen Tetrahedron Animation

Silicon and oxygen are the two most abundant elements in Earth’s crust.90+% minerals (and, therefore, rocks) contain these elements.

O2 -

O2 -

O2 -

O2 -

Si4+

The Silicon-OxygenTetrahedron—anexample of ionic bonding.

Most minerals are Most minerals are composed of only composed of only 8 elements!8 elements!

Crystal Structure Crystal Structure & Physical & Physical PropertiesPropertiesMinerals are solids due to crystalline structure.

Crystal structure determines a mineral’s cleavage (tendency to split along definite planes).Cleavage planes correspond to planes of weak

bonds between the atoms, ions, or molecules.The hardness of a mineral also depends on

the internal arrangement of atoms. (ex. diamond and graphite)

Diamond Diamond and Graphite and Graphite

are both pure carbon, but haveare both pure carbon, but have

different molecular structures.different molecular structures.

Identifying MineralsIdentifying MineralsMineralogy: the study of Mineralogy: the study of

minerals and their minerals and their properties.properties.

Many minerals can be Many minerals can be identified & classified by identified & classified by inspecting them visually and inspecting them visually and performing simple tests to performing simple tests to determine their properties.determine their properties.

Chapter 5 Section 3

Rock-Forming MineralsRock-Forming MineralsMost rock-forming minerals are silicates.

Common rock-forming minerals.ClayQuartzCalciteOlivineDolomitePyroxeneAmphiboleBiotite and Muscovite MicasOrthoclase and Plagioclase Feldspars

•Observed properties Observed properties should be considered should be considered together.together.

A mineral is rarely identified by A mineral is rarely identified by a single property.a single property.

Identifying Mineralsby Inspection

Physical Properties of Physical Properties of MineralsMineralsColorColor

Most easily observed Most easily observed propertyproperty

Some minerals have Some minerals have distinctive colors, but distinctive colors, but color is generally color is generally unreliable for unreliable for identification because identification because impurities or oxidation impurities or oxidation (exposure to oxygen in (exposure to oxygen in air/water) can change air/water) can change a mineral’s colora mineral’s color

Exotic colorations of Exotic colorations of some minerals produce some minerals produce gemstones.gemstones.

However, we still use color as one of the many properties for mineral identification.

Quartz (SiOQuartz (SiO22) exhibits a variety of ) exhibits a variety of colors.colors.

milky quartz

citrine

smokyquartz

amethyst

From:geology.csupomona.edu/alert/mineral/minerals.htm

LusterLusterThe way a The way a

mineral’s mineral’s surface reflects surface reflects lightlight

““metallic” or metallic” or “nonmetallic”“nonmetallic”

Nonmetallic luster:Adamantine – brilliant, like a diamond Dull - non-reflective surfaceEarthy - look of dirt or dried mud Fibrous - the look of fibers/stringsGreasy/oily - the look of grease Pearly - the look of a pearl Resinous - the look of resins such as dried glue or chewing gum Silky - the look of silk, similar to fibrous but more compact Vitreous - the look of glass (most common)Waxy - the look of wax

Galena is a lead sulfide Galena is a lead sulfide that displays metallic that displays metallic

lusterluster

Pyrite is an iron Pyrite is an iron sulfide that displays sulfide that displays

metallic lustermetallic luster

waxy

earthy

pearly

vitreous/glassy

resinousadamantine

dull

fibrous

greasy/oily

silky

Examples of Nonmetallic Luster

Testing Testing Mineral Mineral

SamplesSamples

StreakStreak Color of a mineral in Color of a mineral in its powdered form its powdered form when it is rubbed on a when it is rubbed on a “streak plate” “streak plate” (unglazed porcelain)(unglazed porcelain)

May be same as hand-May be same as hand-specimen or differentspecimen or different

Helpful in Helpful in distinguishing distinguishing different forms of the different forms of the same mineralsame mineral

Streaks of nonmetallic Streaks of nonmetallic minerals are usually minerals are usually colorless or whitecolorless or white

ALWAYS place streak plate on a flat surface.Never hold it in your hand.It can break and cut you.

Examples of Streak

Tendency to break along planes of weak bondingTendency to break along planes of weak bonding Flat, shiny surfaces (1, 2, 3, 4, 6 common)Flat, shiny surfaces (1, 2, 3, 4, 6 common) Described by resulting geometric shapesDescribed by resulting geometric shapes

Number of planesNumber of planes Angles betweenAngles between

adjacent planesadjacent planes

Cleavage

Cleavage Plane Animation

Examples of cleavage – Examples of cleavage – fluorite, halite, and calcitefluorite, halite, and calcite

Mica – one plane of cleavageMica – one plane of cleavage

Muscovite

FractureFractureWhen When

minerals minerals break break unevenly unevenly along rough along rough or curved or curved surfaces.surfaces.

Conchoidalfracture

Mineral HardnessMineral Hardness

The ease or difficulty with The ease or difficulty with which the mineral can be which the mineral can be scratchedscratched

Controlled by the strength Controlled by the strength of bonds between atomsof bonds between atoms

All minerals are compared All minerals are compared to a standard scale called to a standard scale called the the Mohs scale of hardnessMohs scale of hardness Range from 1—talc (softest) to 10Range from 1—talc (softest) to 10

—diamond (hardest)—diamond (hardest)

http://mineral.galleries.com/minerals/elements/diamond/diamond.htm

www.drexel.edu

Mohs Scale of HardnessMohs Scale of Hardness

Softest

Hardest

Steel file

Determining Mineral HardnessDetermining Mineral HardnessYou can determine the approximate You can determine the approximate

hardness of any common mineral by using hardness of any common mineral by using your fingernail, a copper penny, a small your fingernail, a copper penny, a small glass (“scratch”) plate, and a steel file.glass (“scratch”) plate, and a steel file.See whether the mineral scratches or is See whether the mineral scratches or is

scratched by each item.scratched by each item.If the mineral scratches the item, it is harder than If the mineral scratches the item, it is harder than

that item.that item.If the mineral is scratched by the item, it is softer If the mineral is scratched by the item, it is softer

than the item.than the item. This will tell you the mineral’s approximate hardness.This will tell you the mineral’s approximate hardness.

Ex. If the mineral scratches the glass plate (5.5) but Ex. If the mineral scratches the glass plate (5.5) but is scratched by the steel file (6.5), its hardness is is scratched by the steel file (6.5), its hardness is between 5.5 and 6.5 on the Mohs Scale.between 5.5 and 6.5 on the Mohs Scale.

Specific Gravity/DensitySpecific Gravity/Density All minerals have All minerals have

density (mass / volume), density (mass / volume), but some are very but some are very densedense.. Examples: galena, Examples: galena,

magnetite, and gold.magnetite, and gold.

Specific gravity is the Specific gravity is the density of the mineral density of the mineral compared with the compared with the density of water.density of water.

http://www.minerals.net/mineral/elements/gold/gold1.htm

Double refractionDouble refractionFluorescenceFluorescenceTasteTasteMagnetismMagnetismRadioactivityRadioactivityReaction to hydrochloric acidReaction to hydrochloric acidOdor (smell)Odor (smell)

Special Properties

Double RefractionDouble Refraction

“Seeingdouble”

FluorescenceFluorescence

Some minerals will glow when Some minerals will glow when placed under short-wave or placed under short-wave or long-wave ultraviolet rays long-wave ultraviolet rays (“black-light”)(“black-light”)

Franklin and Ogdensburg, NJ Franklin and Ogdensburg, NJ are famous for their fluorescent are famous for their fluorescent mineralsminerals

http://www.sterlinghill.org/Tour%20information.htm

en.wikipedia.org www.hometrainingtools.com

TasteTaste

Halite tastes salty.Halite tastes salty. Remember…Remember…dodo

notnot taste anything taste anything in the laboratory.in the laboratory.

http://mineral.galleries.com/scripts/item.exe?LIST+Minerals+Halides+Halite

MagnetismMagnetism Many iron minerals Many iron minerals

will produce an will produce an invisible magnetic invisible magnetic force field.force field.

““Lodestone” acts Lodestone” acts like a magnet.like a magnet.

Magnetite is Magnetite is attracted to a attracted to a magnet.magnet.

http://www.minerals.net/mineral/oxides/magnetit/magneti4.htm

RadioactivityRadioactivity

Give off subatomic Give off subatomic particles that can particles that can be detected by a be detected by a Geiger counter.Geiger counter.

Exposure can be Exposure can be dangerous to living dangerous to living organisms.organisms.

The “Acid TestThe “Acid Test Reaction with HCl” Reaction with HCl”

Carbonates react Carbonates react with dilute HCl and with dilute HCl and other acids by other acids by fizzing or bubbling fizzing or bubbling (releasing CO(releasing CO22 gas) gas)

Chemical Reactions: Chemical Reactions: Is it Is it calcitecalcite or or dolomitedolomite??

OdorOdor

Sulfur smells Sulfur smells like rotten like rotten eggs.eggs.

Chapter 5 Section 4

Major SilicatesMajor SilicatesMore than 90% of minerals in Earth’s More than 90% of minerals in Earth’s

crustcrustSilicon + Oxygen (and usually 1 or more Silicon + Oxygen (and usually 1 or more

metallic elements)metallic elements)Basic building block = silicon oxygen Basic building block = silicon oxygen

tetrahedrontetrahedronFour oxygen ions surrounding a much Four oxygen ions surrounding a much

smaller silicon ionsmaller silicon ionClassified by how the tetrahedra are Classified by how the tetrahedra are

linked togetherlinked together

O2 -

O2 -

O2 -

O2 -

Si4+The Silicon-Oxygen Tetrahedron

The basis of most rock-forming minerals

SilicateMolecule

Feldspar

Mica

Quartz

Olivine

Silicate Mineral Silicate Mineral ExamplesExamples

Pyroxene

QuartzQuartzMade entirely of tightly bound silica tetrahedraMade entirely of tightly bound silica tetrahedraSiOSiO2 2 (silicon dioxide)(silicon dioxide)Glassy or greasy luster, colorless/white/or Glassy or greasy luster, colorless/white/or

variety of colors, conchoidal or irregular variety of colors, conchoidal or irregular fracture, hardness = 7fracture, hardness = 7Uses: watch movements, prisms, heat lamps, Uses: watch movements, prisms, heat lamps,

lenses, glass, paints, jewelrylenses, glass, paints, jewelryCommon rock-forming mineral (ex. granite)Common rock-forming mineral (ex. granite)

22ndnd most abundant mineral in Earth’s crust most abundant mineral in Earth’s crustMain component of most sandsMain component of most sands

Example:Quartz SiO2

(3-D, Also the Feldspars)

FeldsparsFeldsparsAll types of feldspars have 2 directions All types of feldspars have 2 directions

of cleavage, hardness = 6, pearly lusterof cleavage, hardness = 6, pearly lusterUsed in glass, ceramicsUsed in glass, ceramics

Also has aluminum in addition to silicon Also has aluminum in addition to silicon and oxygen…and oxygen…Other metals include potassium, sodium, Other metals include potassium, sodium,

calciumcalciumImportant rock-forming mineralsImportant rock-forming minerals

Make up ~60% of Earth’s crustMake up ~60% of Earth’s crust

FeldsparsFeldsparsClassified into 2 major groups:Classified into 2 major groups:

potassium feldspars (k-spar, microcline)potassium feldspars (k-spar, microcline)Orthoclase most common (pink/salmon, Orthoclase most common (pink/salmon,

cleavage 2 directions at 90cleavage 2 directions at 90°, most commonly °, most commonly found in granite)found in granite)

Sodium-calcium feldspars (also known Sodium-calcium feldspars (also known as plagioclase feldspar, plag)as plagioclase feldspar, plag)examples: oligoclase, albite, labradorite (white examples: oligoclase, albite, labradorite (white

to gray, cleavage 2 directions to gray, cleavage 2 directions nearlynearly 90 90°, °, striations/fine parallel lines)striations/fine parallel lines)

Feldspar

Aluminum atoms (yellow) with nearby Sodium atoms (green) to balance charge

Other SilicatesOther SilicatesPyroxene familyPyroxene family

Cleavage nearly 90Cleavage nearly 90°°Augite most common of pyroxene family (contain iron Augite most common of pyroxene family (contain iron

and magnesium, dark color, 2 good cleavages, and magnesium, dark color, 2 good cleavages, hardness between 5 & 6)hardness between 5 & 6)

Mica familyMica familySoft silicates (hardness = 2.5)Soft silicates (hardness = 2.5)Perfect cleavage in 1 direction (sheets/flakes)Perfect cleavage in 1 direction (sheets/flakes)Common in granite and gneissCommon in granite and gneiss

Muscovite (silvery/white)Muscovite (silvery/white)Biotite (dark brown/black)Biotite (dark brown/black)

Used in electronics insulators, paints, plastics, Used in electronics insulators, paints, plastics, rubber, roofingrubber, roofing

2_26b2_26b

Single chainSingle chain

Oxygens share electronswith two Silicon atoms

Positive ion

Single chains weakly paired

Example: A Pyroxene

Cleavage planes about 90o

Sheet silicates

Example: A Mica

Other SilicatesOther SilicatesAmphibole mineralsAmphibole minerals

Form long, needlelike crystalsForm long, needlelike crystalsMost common amphibole is hornblende (iron Most common amphibole is hornblende (iron

and magnesium, shiny dark and magnesium, shiny dark green/brown/black, hardness 5-6, 2 good green/brown/black, hardness 5-6, 2 good cleavages at more than 90cleavages at more than 90°, found in igneous °, found in igneous and metamorphic rocks)and metamorphic rocks)

Olivine groupOlivine groupOlive greenOlive greenFerromagnesian silicate (iron, magnesium, Ferromagnesian silicate (iron, magnesium,

silicon, oxygen), hardness = 6.5, glassy/shell-silicon, oxygen), hardness = 6.5, glassy/shell-like fracture, gem-quality olivine = peridot, like fracture, gem-quality olivine = peridot, found in some meteorites)found in some meteorites)

2_26c2_26c

Example: An Amphibole

Cleavages 56 and 124 degrees

Positiveion

Double chains

Tetrahedronfacing down

Tetrahedronfacing up

Positive ionExample OLIVINE

Independent tetrahedra

Fe and Mg

SiO4 -4 Ion

Other SilicatesOther SilicatesKaoliniteKaolinite

Aluminum silicateAluminum silicateFormed by weathering of Formed by weathering of

feldspars and other silicatesfeldspars and other silicatesWhite, hardness = about 2, White, hardness = about 2,

perfect cleavage in 1 directionperfect cleavage in 1 directionOften used in ceramics, paints, Often used in ceramics, paints,

fiberglassfiberglass

Clay MineralsClay Minerals(at high magnification)(at high magnification)

KaoliniteKaolinite(hand specimen)(hand specimen)

note sheet structurenote sheet structure

Common Non-silicate Minerals

Many non-silicate minerals Many non-silicate minerals have economic valuehave economic value

Carbonates contain COCarbonates contain CO33 (carbonate) (carbonate) and metal ionsand metal ionsContained in limestone, marble, and Contained in limestone, marble, and

dolostonedolostoneMany uses (building materials, Many uses (building materials,

manufacturing of paper and medicines)manufacturing of paper and medicines)CalciteCalcite (calcium carbonate) and (calcium carbonate) and

Dolomite Dolomite (calcium-magnesium (calcium-magnesium carbonate) are the two most carbonate) are the two most important carbonate mineralsimportant carbonate minerals

Carbonates

Calcite and DolomiteCalcite and Dolomite

•Calcite = CaCO3

•Calcium carbonate•Colorless or white, hardness = 3, 3 perfect cleavages at more than 90° (rhombohedra), bubbles with acid

•Dolomite•Calcium magnesium carbonate

•Hardness 3.5-4, cleaves into rhombohedra, bubbles in acid only if powdered first•Coarse or fine grains in dolomitic limestone

Oxides and SulfidesOxides and SulfidesContain significant amounts of ironContain significant amounts of ironNot as common as silicates or Not as common as silicates or

carbonatescarbonatesEconomically importantEconomically important

Used to make steel, magnets, car Used to make steel, magnets, car parts, medicines, cosmetics, plastics, parts, medicines, cosmetics, plastics, paintspaints

Iron usually combined with oxygen Iron usually combined with oxygen (oxide) or sulfur (sulfide)(oxide) or sulfur (sulfide)

Oxides and SulfidesOxides and SulfidesOxidesOxides

HematiteHematiteMost common iron oxideMost common iron oxideUsually red (sometimes silvery/metallic), earthy Usually red (sometimes silvery/metallic), earthy

luster, uneven fracture, red-brown streak, luster, uneven fracture, red-brown streak, hardness 5-6hardness 5-6

MagnetiteMagnetiteBlack iron oxideBlack iron oxideAttracted to a magnetAttracted to a magnet

Lodestone is a variety of magnetite (is a Lodestone is a variety of magnetite (is a natural magnet)natural magnet)

Hardness 5.5-6.5Hardness 5.5-6.5

•Sulfides-Pyrite “fool’s gold”

-Most common sulfide mineral-Iron sulfide-Pale brass to golden yellow-Hardness ≈ 6-6-12 sided crystals

Nonsilicate Mineral Nonsilicate Mineral ExamplesExamples

Halite(Halide)

Spinel(Oxide)

Gypsum(Sulfate)

Hematite(Oxide)Calcite

(Carbonate)Pyrite

(Sulfide)Galena

(Sulfide)