Lecture 4

And some rin uphill and down dale,Knapping the chucky stones to pieces wi’ hammers,

Like sae mony roadmakers run daft –They say it is to see how the warld was made.

- Sir Walter Raleigh

Minerals

Webpage for course (daytime)

Webpage for course (nighttime)

Something from the ancient Greek philosopher-scientists

What is a mineral?

A naturally occurring inorganic solid made up of an ordered arrangement of

ATOMS

Difference between minerals and rocks

Atoms, three basic parts

Protons

Neutrons

Electrons

Mass(wt.)

charge

nucleus

electron cloud

Fig. 2.5

Atomic number =

Atomic mass number =

Atomic number = number of protonsAtomic mass number =

number protons and neutrons

Example: Carbon (symbol “C”)atomic number = atomic mass number =

Therefore,6 protons, 6 (12-6) neutrons

Periodic Table

A balanced atom has as many electrons as protons

Electrons are not randomly located

Occur in “shells”

electrons fill shells in a sequential order

1st shell holds up to 2 electrons2nd shell holds up to 8 electrons3rd shell holds up to 8 electrons

Two rules in Nature:

1. electrons occupy shells in a specific order (inner before outer shells)

2. Outer shell that has electrons in it must be full of electrons

Two rules in Nature:1. electrons occupy shells in a specific order

(inner before outer shells)2. Outer shell that has electrons in it

must be full of electrons

Let us develop some characters

Our cast of characters

Our cast of characters

outerelement sym + +/- - # wt. sh. Needs

Hydrogen H

Helium He

Carbon C

Oxygen O

Sodium Na

Chlorine Cl

Iron Fe

Uranium U

So let us meet a hydrogen atom after the Big Bang…

When Harry met Sally

Sodium Chlorine

More formulae

CaCO3 (calcite)KAl2(Si3Al)O10(OH)2 (muscovite)Ca3Al2Si3O12 (garnet)

Silicate minerals

SiO4 tetrahedra

Isolated Olivine

Chains Hornblend

Sheets Mica

Framework Feldspar & Quartz

So, what the atoms are and how to go together determines the characteristics of the mineral:

crystal shapehardnesscleavagechemical propertiesetc. etc.

Graphite and Diamond