1. Lecture Outline Matter and its composition Minerals Mineral groups
Elements and atoms
Bonding and compounds
Minerals
Mineral groups
Silicates, Carbonates,…
Physical properties of minerals
P.24
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP

2. Matter and Minerals
Element – a pure substance with unique chemical properties (on periodic table)
Atoms – smallest particle of an element with that elements properties
Atoms are composed of a
NUCLEUS - with 1. PROTONS (POSITIVE ELECTRICAL CHARGE)
2. NEUTRON (NO ELECTRICAL CHARGE)
ELECTRONS - Negatively charged electrons, orbiting around the nucleus in electron shells
The number of protons in the nucleus determines the Atomic Number (and the name of the element)
ATOMIC NUMBER
Hydrogen, Helium, Carbon, Silicon
Page 27

3. Matter and Minerals All matter composed of atoms Atoms composed of:
Protons (1+) in nucleus
(Total Number of Protons = Atomic Number)
Neutrons (n) in nucleus (Protons+Neutrons = Mass)
Electrons (1-) in orbit around the nucleus
Atoms are composed of a
NUCLEUS - with 1. PROTONS (POSITIVE ELECTRICAL CHARGE)
2. NEUTRON (NO ELECTRICAL CHARGE)
ELECTRONS - Negatively charged electrons, orbiting around the nucleus in electron shells
The number of protons in the nucleus determines the Atomic Number (and the name of the element)
ATOMIC NUMBER
Hydrogen, Helium, Carbon, Silicon
Page 27
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP

5. Three Isotopes of Carbon
Carbon - Atomic Number 6
Page 28
DIAGRAMMATIC VIEW OF THE ISOTOPES OF CARBON
Some atoms of the same elements may have different number of neutrons in their nucleus. In this case these are called ISOTOPES. The occupy the same (iso) place (topo) on the periodic table of elements (see page , Appendix B.
Table of isotopes of carbon
Page 28, figure 2.3The sum of the number of protons and the number of neutrons is the Atomic Mass.
Carbon-12
6 protons
6 neutrons
mass = 12
Carbon-14
6 protons
8 neutrons
mass = 14
Carbon-13
6 protons
7 neutrons
mass = 13
Periodic table, page 666-7
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP

6. Atom combos
compounds – a substance that contains 2 or more different types of atoms
Molecule – the fundamental particle of a compound – one unit. Like H2O molecule consists of 2 Hydrogrens & 1 oxygen atoms
Mixture – a combination of 2 or more compounds not chemically united (salt and pepper – can easily separate)
Ion – a charged “atom”
Positive ion = loss of electrons
Negative ion = gain of electrons
BONDING AND COMPOUNDS
Atoms may join other atoms through a process called bonding.
When two different elements bond, the result is a compound.
gaseous Oxygen is an element
Gold is an element
Silver is an element
Water, Ice, Salt are common examples of compounds.
Most minerals are compounds se page 669 Appendix C look at the composition of several minerals.

7. Bonding and Compounds
Bonding joins atoms to other atoms forming compounds (to make “happy”)
Three types:
IONIC BONDING (metal + nonmetal)
COVALENT (sharing) BONDING
(nonmetal + nonmetal)
METALLIC BONDING (one metal with a sea of electrons)
BONDING AND COMPOUNDS
Atoms may join other atoms through a process called bonding.
When two different elements bond, the result is a compound.
gaseous Oxygen is an element
Gold is an element
Silver is an element
Water, Ice, Salt are common examples of compounds.
Most minerals are compounds se page 669 Appendix C look at the composition of several minerals.

8. Ionic Bonding -- Salt (NaCl)
Negative & positive ATTRACT !!
Sodium metal loses an electron (-1)
becomes Na a positive ion
Chlorine (nonmetal) gains an electron (-1)
becomes Cl a negative ion
Electron transfer
IONIC BONDING
sodium chloride - salt - the mineral HALITE.
Sodium transfers one electron in its outermost shell to the outermost shell of the Chlorine atom
Both atoms end up with a complete outer shell with 8 electrons.
Because Sodium loses an electron it becomes positively charged. Sodium had 11 electrons in its electron shells; finishes with 10 (but still with 11 protons).
Because Chlorine gains an electron it becomes negatively charged. Chlorine had 17 electrons in its electron shells; finishes with 18 (but still with 17 protons)
figure 2.4 page 29
The left diagram shows the relative size of the Chlorine Ions and the Sodium Ions
The right diagram shows the location of the ions in the crystal lattice - the crystal structure. Notice the ions are at right angles to each other. This gives crystals with sides (crystal faces) that are at right angles to each other.
Chlorine (Cl-1)
Sodium (Na+1)
Crystal structure of mineral NaCl, Halite
Want 8 electrons in the outer shell (octet rule)

9. Covalent (Sharing) Bonding
Share so
8 again
Page 29, figure 2.5
Electrons in the outer shells of Carbon are shared in the form of sheets in graphite. The sheets are held together by weaker forces (van der Waals bonds) and the sheets break off easily.
Carbon atoms form a 3-d configuration in diamond and there are no sheets to break off.
Adjacent atoms of carbon share electrons:
Covalent bonding
(in diamond)
Strong bonds
Sheets of carbon atoms
held together by weak
Van der Waals bonds
(graphite)

10. Mineral -- definition Occurs naturally Inorganic Solid Crystalline
regular internal structure
Narrowly defined chemical composition and physical properties (so if hard, always hard… etc)
The term MINERAL, as I mentioned in my previous lecture in one of those terms that is used in the vernacular with a different meaning than it has in geology. The books gives a variety of common meanings for the term mineral; in geology the term has a more specific meaning.
In geology the term means:
Inorganic, solid, crystalline, naturally occurring.
Read Table 1. (page 26) for the differences between
solid, liquid and gas phases of matter.
DEFINITION OF THE WORD MINERAL
Page 73 in book

11. Mineral -- importance Industrial societies depend on
Glass, copper, gold, coal, gypsum, iron……..
Gem minerals
Diamonds, rubies, topaz…...
Classification of rocks
Based largely on mineral contents
Minerals are important in geology for a number of reasons:
1. The components of rocks - especially for fundamentals of geology students
2. Gemstones
3. Gold
4. Industrial purposes
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP

13. The Naica Mine of Chihuahua, Mexico, is a working mine that is known for its extraordinary crystals. Naica is a lead, zinc and silver mine in which large voids have been found, containing crystals of selenite (gypsum) as large as 4 feet in diameter and 50 feet long. The chamber holding these crystals is known as the Crystal Cave of Giants, and is approximately 1000 feet down in the limestone host rock of the mine. The crystals were formed by hydrothermal fluids emanating from the magma chambers below. The cavern was discovered while the miners were drilling through the Naica fault, which they were worried would flood the mine. The Cave of Swords is another chamber in the Naica Mine, containing similar large crystals.

14. Crystal form
Minerals are crystalline solids, can grow to perfect crystals with perfect faces
under ideal conditions (called euhedral)
MINERALS
Minerals are crystalline substances. Under certain conditions they can grow to perfect shapes and each crystal has its own characteristic crystal habit
MINERAL CRYSTAL HABITS
A=6 SIDES -- GALENA
B=12 SIDES C GARNET
C=8 SIDES C DIAMOND
D=6-SIDED PRISM WITH PYRAMID TERMINATIONS C QUARTZ
Internal arrangement of te atoms or ions or molecules determines the crystal shape.
Where the planes of weakness occur is where the mineral breaks off easily. The planes are called the planes of cleavage.
6 sides - Galena
12 sides - Garnet
8 sides - Diamond
6-sides - Quartz

15. Interfacial angles Interfacial angles are constant for all crystals.
Faces of Quartz form 120 degree angles – always if they have room to grow !
The angles between crystal faces are constant. The internal arrangement of each type of crystal is constant and each crystal is composed of smaller identical building blocks. The arrangement of these blocks determines the crystal form.
Page 31

16. 7 Major Mineral Groups determined by the type of chemical bonding
1. Silicates - contain the Silicon-oxygen Tetrahedral (SiO4)-4
a. Ferromagnesian silicates (Fe+2 and Mg+2)
Non-ferromagnesian silicates
2. Carbonates - contain CO3 -2
with either Ca +2, Mg +2, or both
MINERAL GROUPS
See page 39, table 2.6 for a summary
Silicate minerals or SILICATES Include SILICON in their composition.
Quartz is pure silica. Most other silicates posses other elements as part pf their composition.
Silicates are important because they are amongst the most common rock forming minerals.

17. 7 Major Mineral Groups determined by the type of chemical bonding
3. Halides – Contains Cl -1 , F -1 , or Br with a metal (like NaCl)
Sulfides – S -2 with a metal like lead or iron (PbS)
Oxides – O-2 with a metal like iron (Fe2O3)
(or even ice ! H2O)
Sulfates – SO4 -2 bonding with a metal (CaSO4)
Native elements like Gold & Silver !
MINERAL GROUPS
See page 39, table 2.6 for a summary
Silicate minerals or SILICATES Include SILICON in their composition.
Quartz is pure silica. Most other silicates posses other elements as part pf their composition.
Silicates are important because they are amongst the most common rock forming minerals.
Page 33

18. Importance of Silicates
Earth’s crust = 28% Silicon & 47% Oxygen (air is 78% Nitrogen & 21% oxygen)
Silicates are most abundant minerals
95% of Earth’s crust
Two thirds of all minerals are silicates
Silica tetrahedra form strong bonds
Therefore: Silicates are an important rock-forming mineral group!!

19. Silicate minerals silica tetrahedra Building blocks of
Two major types of silicates:
Ferromagnesian silicates rich in iron (Fe) and magnesium (Mg)
Non-ferromagnesian silicates poor in iron and magnesium rich in silica
Building blocks of
silicate minerals --
silica tetrahedra
(SiO4)-4
The silica tetrahedron has a negative charge of four and so combines with other ions with a positive charge or it shares its oxygen with other tetrahedra.
Silica is abundant in the crust of the Earth. The silica tetrahedra combine readily with other elements to form silicate minerals and the bonds holding them together are strong. Therefore silicate minerals are abundant and many of them are not easily weathered and decomposed.
Silica Tetrahedron (SiO4)-4
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP
Page 32

20. Arrangements of Tetrahedra
Olivine
Pyroxene
Amphibole
The Silica Tetrahedron combines with other elements or other tetrahedra in a variety of ways:
Note the arrangements of:
isolated tetrahedra == olivine
single chains == pyroxene
double chains ==amphibole
sheets == micas
3-dimensional framework == quartz
Micas
Quartz
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP
Page 33, fig. 2.10

21. Common Silicate Minerals
The Light Silicates (non-ferromagnesian)
Feldspar Group – most common
Pink (orthoclase) with Potassium (K+1)
Dark to light (Plagioclase) with Ca +2 and Na +1
The Silica Tetrahedron combines with other elements or other tetrahedra in a variety of ways:
Note the arrangements of:
isolated tetrahedra == olivine
single chains == pyroxene
double chains ==amphibole
sheets == micas
3-dimensional framework == quartz
Quartz (SiO2) – clear unless it has inclusions
(impurities)
3. Mica - Muscovite

22. Common Silicate Minerals
The Dark Silicates (ferromagnesian)
Mica - Biotite
Amphibole
The Silica Tetrahedron combines with other elements or other tetrahedra in a variety of ways:
Note the arrangements of:
isolated tetrahedra == olivine
single chains == pyroxene
double chains ==amphibole
sheets == micas
3-dimensional framework == quartz
3. Pyroxene
4. Olivine
5. Garnet

23. Physical Properties of Minerals
Color
Streak
Luster
Cleavage
Fracture
Hardness
Specific gravity (density)
Crystal habit
Taste
Magnetism
Reaction to Acid
…….
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP

24. Color
Color is diagnostic for some minerals: Olivine is green, galena is silver-gray
Color is important for metallic minerals
Clear, colorless or transparent minerals have many color variations due to impurities and slight variations in chemical composition
Quartz may be colorless, white, pink, purple, yellow, black, gray, etc.
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP

25. Streak Streak refers to the color of a powder mineral
Produced by scraping the mineral against an unglazed ceramic plate.
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP

26. Luster Appearance of a fresh mineral surface in reflected light
Two types: metallic or nonmetallic
Nonmetallic luster may be:
vitreous or glassy - the luster of glass (quartz)
resinous - luster of resin (sphalerite)
pearly - (talc)
silky - (asbestos)
dull or earthy - no luster (kaolinite)
adamantine - brilliant (diamond)
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP

27. Cleavage
Tendency of a mineral to break along parallel planes or directions of weakness in regular patterns-
One direction - micas
Two directions feldspar, pyroxene
Three directions - halite, galena
Four directions - fluorite
Six directions - sphalerite
Page 37
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP

28. Fracture Mineral breakage along irregular surfaces
Important in minerals without cleavage
Occurs in minerals with bonding equally strong in all directions
Page 37
Quartz with Conchoidal fracture
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP

29. Hardness Resistance to being scratched Related to Mohs Hardness Scale
Diamond 10
Corundum 9
Topaz 8
Quartz 7
Orthoclase 6 Steel file (6.5)
Apatite 5 Glass (5.5- 6)
Fluorite 4
Calcite 3 Copper penny (3.0)
Gypsum 2 Fingernail (2.5)
Talc 1
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP
Page 38

30. Crystal Form Manifestation of internal atomic arrangement
Quartz
Crystal Form
Manifestation of internal atomic arrangement
All minerals are crystalline
microscopic crystals common
large crystals rare
Crystal form is characteristic of certain minerals
Quartz
Fluorite
Calcite
Galena
Fluorite
Calcite
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP
Page 36

31. Carbonates, Sulfates, Sulfides, Oxides
Carbonates contain the ion (CO3)-2
(CO3)-2 can combine with
Calcium (Ca) -- to form Calcite [CaCO3]
or with Magnesium (Mg) to form Dolomite [Ca, Mg (CaCO3)2]
Sulfates contain (SO4) Gypsum
Sulfides contain sulfur (S-2) Galena
Oxides contain an element combined with Oxygen Hematite
Claude Spinosa
© 1998 Wadsworh Publishing Company /ITP