Download Minerals:

Atoms, Compounds,
Minerals and Rocks
Atoms

Atoms - the smallest unit of an element that retains the physical and chemical
properties of that element

Made up of a nucleus, and a “cloud” of electrons

Nucleus made up of protons and neutrons

Number of protons determines which type of Element the atom is

Element - distinctive type of matter with specific phyisical and chemical
properties

Examples: Iron, Oxygen, Hydrogen, etc.

Generally grouped as Metals or Nonmetals
Compounds

Compound - substances made by the bonding of chemical elements
(from chemical reactions). Compounds are comprised of two or more
different elements.
Chemical bonds may be made by

–
–

sharing electrons between atoms - covalent bonds
lending or borrowing electrons with mutual attraction of oppositely
charged atoms - ionic bonds
The properties of compounds are dramatically different from those of
the elements that comprise them
A Mineral is
Naturally occurring
 Inorganic (not made from animals or
plants)
 Solid
 with a definite chemical composition
(formula)
 and an orderly arrangement of atoms
(crystal structure)
 Minerals are chemical compounds

Crystal Structure

How do crystals form?

Atoms must be free to
move

Chemical bonds dictate
the geometric arrangement
of atoms

Crystal is external
manifestation of order at
atomic level
Crystal Structure

Atoms must be free to
move

Under what conditions
does this occur?

In a melt (magma)

In solution (dissolved in
water)
Abundance of chemical elements
in Earth’s Crust
O – 46.6%
 Al – 8.1%
 Ca – 3.6%
 K – 2.6%
 Other – 1.7%

Si – 27.7%
Fe – 5.0%
Na – 2.8%
Mg – 2.1%
Silicate Minerals
O and Si make up nearly 75% of crust
 Most common elements should make up
most common minerals
 Common “rock-forming” minerals are
silicates
 Silicates have Si, O and other elements such
as Fe, Mg, Al, Na, K, Ca

Silicon-Oxygen Tetrahedron



“Building Block” of Silicate minerals
Si surrounded by 4 O
O may be shared so that tetrahedra link together
Sharing Tetrahedra
Olivine – Fe,Mg silicate
Single Tetrahedra
Pyroxene – Fe, Mg, Al silicate
Single Chains
Amphibole – Fe, Mg, Ca, Na, Al, F
silicate
Micas (biotite, muscovite) – K, Al
+/-Ca, Mg, Fe silicates
Complex silicates


Quartz SiO2
Feldspars
– Na,Ca silicates
Plagioclase
– K, Al silicates

Other minerals
Bowen’s Reaction Series
Other Mineral “Families”
Halides – contain metals and Cl, F, I, etc.
 Carbonates – contain metals and CO3
 Oxides/Hydroxides – contain metals and O
or OH
 Sulfides – contain metals and S
 Phosphates – contain metals and PO4
 “Native” Elements – pure elements

So, What is a Rock?



A Rock is:
An “aggregate” of minerals
Usually, a mixture of two or more minerals, each
of which remains distinct