Volume Mass
Crust
1%
0.5%
Mantle
83%
67%
Core
16%
32.5%
(Outer core)
15.5%
31%
(Inner core)
0.7%
1.5%
What’s a rock?
http://www.totoro.org/emo/strip2.shtml
What’s a
mineral?
Inorganic
Crystalline
• Photonic silicon
crystal
Three Types of Rock: Igneous, Sedimentary, Metamorphic
Rock: A solid, cohesive aggregate of grains of one or more MINERAL.
Mineral: A naturally occurring, solid, inorganic element or compound,
with a definite composition (or range of compositions), usually
possessing a regular, internal crystalline structure.
Example:
Rock = Granite
Minerals = Quartz, Feldspars,
Biotite, etc.
Rock can be made out of only
one mineral…but multiple grains
CRYSTAL - A mineral grain displaying the characteristics of its atomic structure.
Defined on: chemistry (which elements?) and structure (how are they arranged?)
WHY DO MINERALS FORM?
(Why not just separate elements?)
 Atoms are attracted - bond together to form large
mega-molecules with same pattern  crystal
Atoms are constantly in motion, jumping from one
structure to another
Certain combinations of elements are stable
If molecule is not stable, it breaks apart
If molecule is stable, it continues to grow
“Evolution” - survival of the fittest - of minerals!
IONIC BOND
Ex: Halite (salt)
COVALENT
BOND
Ex: Diamond
METALLIC BOND:
Electrons are free to
move about between
atoms
For a Mineral to be Stable:
1. Ionic charges sum to ZERO
2. Ion sizes must be compatible
(sizes determined by electron cloud)
Imagine what happens in a cooling magma chamber: Like a game of musical
chairs with the atoms “sitting down” into growing crystals
Early Earth
Bulk Composition of Earth
Sulfur (S), 1.9
Nickel (Ni), 2.4
Magnesium
(Mg), 13
Calcium (Ca),
1.1
Aluminum
(Al), 1.1
%Weight
Iron (Fe), 35
Silicon (Si), 15
Oxygen (O), 30
Composition of the Crust
Sodium
(Na), 3
Potassium
(K), 3
Magnesium
(Mg), 2
%Weight
Aluminum (Al),
Calcium
Iron (Fe), 5
8
(Ca), 4
Silicon (Si), 28
Oxygen (O), 47
COMPOSITION OF THE EARTH'S CRUST
Element
Oxygen (O)
Silicon (Si)
Aluminum (Al)
Iron (Fe)
Sodium (Na)
Calcium (Ca)
Magnesium (Mg)
Potassium (K)
% Atoms
62.6
21.2
6.5
1.9
2.6
1.9
1.8
1.4
% Weight
46.6
27.7
8.1
5.0
2.8
3.6
2.1
2.6
% Volume
91.7
0.2
0.5
0.5
2.2
1.5
0.4
3.1
Most minerals are variations on silicon and oxygen: silicates
Silica Tetrahedron:
Different silicate structures: single tetrahedra, single chains, double chains,
sheets, 3D structures (other atoms fill in the spaces in between).
Slightly changing the different elements that combine with silica greatly
changes the mineral that results, or the characteristics of the mineral.
Ex/ Different forms of quartz
The
ROCK
CYCLE
The
ROCK
CYCLE:
Connected
with the water
cycle and the
carbon cycle
Ex/ Multiple
paths that any
given atom can
take through
the system