Minerals

(Chemical bonds, Crystals)

Rocks

Wholeness

God

God

Nothing

Something

Atoms

(Chemical bonds, Crystals)

Chemical elements

Theme 4.

Cristals and Minerals

4.1. Elements

4.2. Identifying minerals

4.3. Common minerals

4.1. Elements

Source: http://oxford-labs.com

4.1. Elements

Source: Understanding Earth –

J.Grotzinger, T.H. Jordan, F.

Press, R. Siever

4.1. Elements

Crust Globe

Oxygen O 45.20 29.50

Silicon Si 27.20 15.80

Aluminium Al 8.00 1.10

Iron Fe 5.80 34.46

Percent by mass (%)Element Symbol

after Skinner and Porter, 1980

Iron Fe 5.80 34.46

Calcium Ca 5.06 1.10

Magnesium Mg 2.77 12.70

Sodium Na 2.33 0.60

Potassium K 1.68 0.10

Other 1.96 5.64

4.1. Elements

Individual

Person

AtomsIons

Minerals

(Chemical bonds, Crystals)

Rocks

Wholeness

God

God

Nothing

Something

Atoms

(Chemical bonds, Crystals)

Chemical elements

4.1. Elements

Chemical bonds

-Covalent bonds

-Ionic bonds-Ionic bonds

-Metallic bonds

-Other bonds

4.1. Elements

Covalent

bonds –

strong bonds

Source: Understanding Earth – J.Grotzinger,

T.H. Jordan, F. Press, R. Siever

Source: Internet

Diamond

4.1. Elements

Ionic bonds – weak bonds

Source: Understanding Earth – J.Grotzinger, T.H. Jordan, F. Press, R. Siever

4.1. Elements

Ionic bonds – weak bonds

Source: Understanding Earth – J.Grotzinger, T.H. Jordan, F. Press, R. Siever

4.1. Elements

Ionic bonds – weak bonds

Source: Understanding Earth – J.Grotzinger,

T.H. Jordan, F. Press, R. Siever

Halite

4.1. Elements

Metallic bonds – complex bonds

In a metallic bond, bonding electrons are delocalized

over a lattice (or a sea) of atoms.

Source: Internet

Pyrite

AntimonitGalena

4.1. Elements

Other bonds – intermolecular bonds

-Van der Waals bonds

-Hydrogen bonds-Hydrogen bonds

Minerals

(Chemical bonds, Crystals)

Rocks

Wholeness

God

God

Nothing

Something

Atoms

(Chemical bonds, Crystals)

Chemical elements

4.2. Identifying minerals

Crystal means:

- a homogenous solid

- in which atoms are catched in different chemical

bonds

- and its are arranged in an orderly, repeating, three-

dimensional array.

4.2. Identifying minerals

All crystals possess certain elements of

symmetry.

The angles between the faces are the same in

the same type of crystal (perfect or imperfect).

4.2. Identifying minerals

4.2. Identifying minerals

Centre of symmetry:

- a crystal possesses when all its faces occur in

parallel pairs on opposite sides of the crystal.

Axis of symmetry:

- is a line through a crystal such that a complete- is a line through a crystal such that a complete

rotation of 360° about it produces more than one

identical view.

Plane of symmetry:

- divides the crystal into halves, each of which is a

mirror image of the other without rotation.

4.2. Identifying minerals

On the basis of the number and type of symmetry

elements present in naturally formed crystals, there

are seven crystal systems.

Cubic system

(izometric)

Tetragonal system

Hexagonal system

4.2. Identifying minerals

Orthorhombic system

Trigonal system

(rhombohedral)

Triclinic system

Monoclinic system

Minerals

(Chemical bonds, Crystals)

Rocks

Wholeness

God

God

Nothing

Something

Atoms

(Chemical bonds, Crystals)

Chemical elements

4.2. Identifying minerals

Mineral is:

- a naturally occurring, solid crystalline substance,

- generally inorganic,- generally inorganic,

- with a specific chemical composition.

4.2. Identifying minerals

Minerals form by the process of crystallization, in

which the atoms of a gas or liquid come together in

the proper chemical proportions and crystalline

arrangement.

During crystallization, the initially microscopic crystalsDuring crystallization, the initially microscopic crystals

grow larger, maintaining their crystal faces as long as

they are free to grow and the time of cooling it's

large.

The most large mineral crystals form in open spaces in

rocks, such as fractures or cavities.

4.2. Identifying minerals

Source: Internet

4.2. Identifying minerals

Cubic system (izometric)

Galena

Halite

Source: Internet

Pyrite

Fluorspar

Diamond

4.2. Identifying minerals

Tetragonal system

Cassiterite

Scheelitee

Source: Internet

Stannite

Zircon

4.2. Identifying minerals

Hexagonal system

Apatite

Zincite

Beryl

Source: Internet

Graphite

4.2. Identifying minerals

Orthorhombic system

Sulfur

Topaz

Baryte

Source: InternetOlivine

4.2. Identifying minerals

Trigonal system (rhombohedral)

Calcit

Source: Internet

Quartz

Siderite

Corundum

4.2. Identifying minerals

Monoclinic system

Orthoclase Augit

Source: Internet

Wolframite

Gypsum

4.2. Identifying minerals

Triclinic system

Kaolinite

Albite

Source: Internet

Kyanite

Chalcanthite

4.2. Identifying minerals

The crystal faces of a

mineral are the

external expression

of the mineral'sof the mineral's

internal atomic

structure.

Source: Internet

4.2. Identifying minerals

As well as crystallography, other important properties

are used to identify minerals, as follows:

• colour and streak,

• cleavage and fracture,

• hardness,

• lustre,lustre,

• crystal habit,

• specific gravity,

• transparency,

• reaction with acid,

• tenacity,

• taste and magnetic properties.

4.2. Identifying minerals

Colour and streak

The colour of a mineral:

- is that seen on its surface by the naked eye,

- depend on the impurities present in light-coloured

minerals,minerals,

-is usually a general rather than specific guide to

which mineral is present.

The streak is the colour of the powdered mineral.

4.2. Identifying minerals

Colour and streak

Mineral Colour Streak

Galena grey black

Examples:

Galena grey black

Hematite black, red, brown reddish brown

Olivine olive green, reddish white

Orthoclase white grey, yellow, reddish white

4.2. Identifying minerals

Cleavage and fracture

Most minerals can be cleaved along certain specific

crystallographic directions which are related to planes

of weakness in the atomic structure of the mineral.

These cleavage directions are usually parallel to one

of the crystal faces.

Calcite

Source: Geology for Civil Engineers – A.C.McLean, C.D. Gribble

4.2. Identifying minerals

Cleavage and fracture

Examples:

Mineral Number of cleavage directions

Quartz no cleavageQuartz no cleavage

Micas 1

Pyroxenes 2

Amphiboles 2

Galena 3

Fluorite 4

4.2. Identifying minerals

Cleavage and fracture

Fracture is:

- a surface formed by breaking the mineral along a

direction which is not a cleavage;direction which is not a cleavage;

- usually more irregular than a cleavage plane.

Quartz

Source: Internet

Garnet

4.2. Identifying minerals

Hardness

Hardness is a measure of the ease with which the

surface of a mineral can be scratched.

Mohs, an Austrian mineralogist, devised a scale basedMohs, an Austrian mineralogist, devised a scale based

on the ability of one mineral to scratch another.

4.2. Identifying minerals

Hardness – Mohs’ scale

Source: Geology for Civil Engineers – A.C.McLean, C.D. Gribble

4.2. Identifying minerals

Lustre

How the surface of a mineral reflects light gives it a

characteristic luster.

Luster is controlled by the kinds of atoms present andLuster is controlled by the kinds of atoms present and

their bonding, both of which affect the way light

passes through or is reflected by the mineral.

Source: Internet

4.2. Identifying minerals

Lustre

Source: Geology for Civil Engineers – A.C.McLean, C.D. Gribble

4.2. Identifying minerals

Cristal habitThe development of an individual crystal, or an

aggregate of crystals, to produce a particular external

shape depends on the temperature and pressure

during their formation.

Since the mode of formation of a mineral isSince the mode of formation of a mineral is

sometimes a clue to what it is, this shape or crystal

habit is of use in the identification of some minerals.

Source: Internet

4.2. Identifying minerals

Cristal habit

Source: Geology for Civil Engineers – A.C.McLean, C.D. Gribble

4.2. Identifying minerals

Specific gravityThe specific gravity or density of a mineral can be

measured easily in a laboratory, provided the crystal is

not too small.

2.00 g/ccm – 21.5 g/ccm

4.2. Identifying minerals

Specific gravity

- low specific gravity minerals include silicates,

carbonates, sulphates and halides,

- medium specific gravity minerals include metallic

ores such as sulphides and oxides,ores such as sulphides and oxides,

- high specific gravity minerals include native metallic

elements such as pure copper, gold and silver.

4.2. Identifying minerals

Transparency

Transparency is a measure of how clearly an object

can be seen through a crystal.

Source: Internet

4.2. Identifying minerals

Transparency

Source: Geology for Civil Engineers – A.C.McLean, C.D. Gribble

4.2. Identifying minerals

Reaction with acidWhen a drop of cold 10% dilute hydrochloric acid is

put on certain minerals, a reaction takes place.

In calcite (CaCO3), bubbles of carbon dioxide make the

acid froth, and in some sulphide ores, hydrogen

sulphide is produced.sulphide is produced.

Source: Internet

4.2. Identifying minerals

Tenacity

Tenacity is a measure of how the mineral deforms

when it is crushed or bent.

Source: Internet

4.2. Identifying minerals

Tenacity

Source: Geology for Civil Engineers – A.C.McLean, C.D. Gribble

4.2. Identifying minerals

Taste and magnetic properties

Taste and magnetic properties are diagnostic of a few

minerals.minerals.

4.2. Identifying minerals

Recapitulation – physical properties of minerals

Source: Understanding Earth – J.Grotzinger, T.H. Jordan, F. Press, R. Siever

4.3. Common minerals

There are more than 4000 known minerals.

CLASS DESCRIPTION SOME MINERALS INCLUDED

Includes native

metals, inter-metallic

antimony, bismuth, copper,

diamond, carbides, electrum,

4.3. Common minerals

Element

metals, inter-metallic

elements, semi-

metals, non-metals,

and natural alloys.

diamond, carbides, electrum,

gold, graphite, nitrides ,

phosphides, silicides, silver,

sulfur

These are minerals that

have Sulfur (S) in their

arsenides, antimonides,

bismuthinides, bornite,

chalcocite, chalcopyrite,

4.3. Common minerals

Sulfidecomposition in the

form of S2-as the major

anion. Includes

Sulfosalts.

cinnabar, covellite, galena,

molybdenite, oOrpiment,

pentlandite, pyrite, realgar,

selendides, sulfosalts,

tellurides

Oxide

These are minerals that

have oxygen in their

composition that is not

part of water. It also

includes the hydroxide

(OH) minerals

bauxite, chromite,

corrundum, hematite, Iice,

ilmentite, magnetite, spinel,

rutile, uranite,

4.3. Common minerals

(OH) minerals

Halide

Those Minerals that

have Cl (chlorine), Br

(bromine), F (fluorine),

or I (iodine) at the end

of their formula.

halite, fluorite, sal amoniac,

sylvite alum)

Carbonate

Those minerals minerals

containing the anion

(CO )2−. Also includes

aragonite, azurite,

borax, calcite, dolomite,

nalachite, niter,

4.3. Common minerals

Carbonate (CO3)2−. Also includes

nitrate (NO3) and borate

(BO3) containing minerals.

nalachite, niter,

rhodochrosite,

smithsonite, ulexite

Sulfate

Those minerals

minerals containing

the anion (SO4)2−

anglesite, anhydrite, barite,

celestine, crocoite,

chromate, gypsum,

molybdate, xelenate,

xulfite, tellurate, tungstate

Includes any mineral

4.3. Common minerals

Phosphate

Includes any mineral

with a tetrahedral

unit (AO43-) where A

can be Phosphorus

(P), Antimony (Sb),

Arsenic (As) or

Vanadium (V).

apatite, autunite,

turquoise, nanadinite,

nariscite, wavellite

Includes minerals

composed largely of

silicon and oxygen,

having the (SiO2) , with

amphiboles, aquamarine,

berlys, emerald, feldspars,

garnets, goshenite, jade,

kunzite, kyanite, micas,

4.3. Common minerals

Silicatehaving the (SiO2) , with

the addition of ions such

as aluminum,

magnesium, iron, and

calcium.

kunzite, kyanite, micas,

olivines, pyroxenes, quartz,

sodalite, talc, topaz,

tourmalines, staurolite,

zeolites

4.3. Common minerals

Common silicate minerals are polymorphs of silicate ions

and often other elements.

Source: Understanding Earth – J.Grotzinger, T.H. Jordan, F. Press, R. Siever

4.3. Common minerals

Source: Understanding Earth – J.Grotzinger, T.H. Jordan, F. Press, R. Siever

4.3. Common minerals

Source: Understanding Earth – J.Grotzinger, T.H. Jordan, F. Press, R. Siever

4.3. Common minerals

Source: Understanding Earth – J.Grotzinger, T.H. Jordan, F. Press, R. Siever

4.3. Common minerals

Source: Understanding Earth – J.Grotzinger, T.H. Jordan, F. Press, R. Siever