Download November 29, 2011 - Perry Local Schools

November 29, 2011
1. Pick up your packet.
2. Have a seat quietly.
Minerals
A substance must be/have the following to be considered a mineral:
1.
naturally occurring
2.
inorganic
3.
solid
4.
definite chemical composition
5.
crystal structure
Important things to remember:
A.
Minerals are what rocks are made of
B.
There are over 3000 minerals known on Earth.
C.
Oxygen and Silicon are common in many minerals.
Minerals are identified by:
A. Color: Not very dependable because color may vary from mineral
(quartz) to mineral and different minerals have similar color.
Some are even colorless.
B.
Luster: The way light is reflected
a. Metallic: hard shiny look, all light is reflected. It looks like metal
(Galena)
b. Non-metallic: doesn‛t look like metal, it can be shiny (don‛t get
confused) but it doesn‛t look like metal. Examples: dull,
earthy, glassy, greasy
C.
Streak: Powdered form of a mineral
a.
use a streak plate to determine streak
D.
Hardness: Resistance to scratching
a.
Moh‛s hardness scale 1-10 (1=soft 10=hard)
b.
Scratch another mineral, if it scratches it the mineral is harder (glass
plate 5.5, fingernail 2.5, penny 3.5, iron nail 4.5, streak plate 7,
diamond 10)
E.
Cleavage: Tendency of a mineral to break along flat planes because of weak
bonds all because of INTERNAL ARANGEMENT. Fracture: do not
follow a pattern, very irregular.
F.
Density: ratio between mass and volume. Heft or how “heavy” it feels.
Ex: Gold 19, lead 12, water = 1
G.
Unusual Properties: Calcite reacts with acid, halite its
salty, magnetite is magnetic, talc and graphite are greasy
ROCKS
Rocks: Rocks are composed of minerals-- most have many (two or more), some have one.
Rocks such as granite, basalt and sandstone contain a variety of minerals.
Rocks are classified according to their origin (how they were formed).
A.
Igneous
B.
Sedimentary
C.
Metamorphic
Igneous: Cooling and solidification of molten (liquid) rock
Sedimentary: Compaction, cementing. lithification of layers of sediment.
Metamorphic: form when any rock is changed due to exposure to heat and pressure.
IGNEOUS ROCKS
1.
2.
3.
4.
Form from hot rock (magma or lava) cooling.
When the liquid cools to about 600 -1000 *C it solidifies.
During solidification, crystals form and grow.
Crystal size gives a clue as to how quickly the rock solidified.
Large crystals = slow cooling
Small crystals = fast cooling
No crystals (non crystalline) = really really fast cooling
Intrusive and Extrusive
Intrusive (Plutonic): inside the earth, slow cooling = large crystals.
granite, gabbro
Extrusive (Volcanic): on Earth‛s surface, fast cooling = small crystals or NO crystals.
basalt, obsidian, pumice
Igneous Rock Classification:
1.
Color Light or Dark
a.
Light = Felsic, FEldspar and SIlica
b.
Dark = Mafic, MAgnesium and Iron (FE)
2.
Texture:
a.
glassy = fast cooling
b.
fine = fast cooling
c.
coarse = slow cooling
d.
very coarse = very slow cooling
e.
vesicular = Gas Pockets
SEDIMENTARY ROCKS
HOW THEY FORM: Form from pieces of other rock (sediments) that are
compacted and cemented together.
The sediments are deposited in horizontal layers, at the bottom of a lake or
ocean and usually carried by an agent of erosion. These particles start off
irregularly shaped but usually end up nice and rounded or filed down because of
their long journey (wind, water, glaciers).
The process of weathering breaks them down, erosion carries them away.
Sedimentary are the most common on the Earth‛s surface.
There is usually a thin layer over metamorphic and igneous rocks.
Sedimentary rocks are broken down into 3 types:
1.
Clastic: (fragmental) rocks are formed by compaction and cementation
of sediments.
EX: shale, sandstone, conglomerate, usually contain fossils
2.
Organic: Once living things Coal and Limestone
3.
Crystaline: Evaporation of seawater or rock salt.
*May indicate the area was once covered by an ocean.
METAMORPHIC ROCKS
Form when sedimentary, Igneous, or Metamorphic rocks are CHANGED by
exposure to heat and/or pressure.
They have gone through significant changes but NOT COMPLETELY melted
A. Usually occurs deep within the earth
B. May cause structures such as layering to become DISTORTION or to
disappear.
C. May cause new minerals to grow or form.
D. Crystal alignment is known as FOLIATION (Schist) SHINY
E. Minerals may separate into light and dark called (BANDING). Gneiss
How do they get to the surface?
Uplifting, mountain building and plate tectonics, etc.
2 types of metamorphism:
1. Regional metamorphism: The process by which rocks are
transformed by heat and pressure deep within the earth.
2. Contact metamorphism: rocks are altered at or near the Earth's
surface as a result of nearby magma/lava. The rocks get baked. Not a
lot of pressure so the rocks don‛t change as much as regional
The Rock Cycle
- Natural Changes
- Our planet has a limited mass. Our planet is a closed system, so all rocks change
through a process that is continuously occurring.
The rock cycle illustrates several important points
1.
All rocks are made from other rocks (except coal).
2.
Rocks are classified on basis of origin.
3.
There are a variety of ways rocks can change in response to changing
conditions at the surface or below
Changes take thousands or millions of years!
Some rocks show different origins.
Ex. You may find granite and gneiss in a conglomerate rock. Even though
conglomerate is sedimentary, the rocks inside it may not be sedimentary.