1. Rocks and the rock cycle man!

2. Rocks vs. Minerals Most rocks are composed of more than one mineral
Polymineralic= rocks containing more than one mineral
Ex: Granite- has quartz, feldspar, mica and hornblende
“Monomineralic”=a rock composed of only one
Example: Halite
Some rocks don’t contain ANY minerals:
Ex: Coal – made from organic matter (dead plant remains)

3. Types of Rocks
Rocks are first classified into three groups according to how they formed
1.)Igneous- solidification of molten rock
2.)Metamorphic-recrystalization with ↑ T & P
3.)Sedimentary- compaction and cementation
Rocks are further classified according to :
texture and
mineral content

5. The rock cycle

7. Driving forces of the Rock cycle:
1.) Heat from earth’s interior
For metamorphism
For the motions of the plates (lithosphere)
2.) Energy from the sun
3.) Meteorite Impacts
4.)Gravity
*All of these forces create: Uplift (rocks moving to surface), erosion, weathering, pressure and melting

8. Sedimentary Rocks

9. Sedimentary Rocks 3 types: Clastic, Chemical, Biologic
Most formed from Burial, Compaction, & Cementation of weathered down material (gravels, sands, clay)
Sed. Rocks can be made from ANY type of other rock fragments (clasts)

10. How It all Starts:
Weathering and Erosion: Running water erodes pre-existing rock and carries these sediments into rivers, lakes, and oceans
Deposition:These sediments are then dumped, and form flat “layers” as new sediment is continually deposited
Compaction: As sediments compress the layers are dewatered as water in the pore space is squeezed out

11. What holds it all together?
Cementation: dissolved minerals precipitate out in the saturated water of pore spaces in sediments
This is the “Glue” of the rock!
Common cements in rock: calcite, quartz, hematite (brown/red)

12. 1.)Inorganic Clastic Rocks – contain mostly solid sediments cemented together
Conglomerate- made of many different clasts
Sandstone- made of sand
Shale-made of tiny pieces of clay

13. Breccia Vs. Conglomerate ↓ ↓

14. 2.)Chemical Rocks
Evaporites When minerals precipitate (drop) out of water and form intergrown crystals
Remember, Minerals Precipitate when:
1.) Evaporation occurs (halite)
AND
2.)Saturation Occurs
(calcite, gypsum)

15. Organic (living) Reactions
3.) Bioclastic or Biologic rocks:
Form when living organisms take in dissolved minerals
Ex: A clam makes a shell
A coral makes a skeleton
You make bones and teeth
When these organisms die, their material is buried, compacted, and cemented the same, but it is biologic material

16. Bioclastic Rocks Coquina Fossil Limestone (made of shells)
Coal: Made of plant matter

17. Sedimentary Rocks are further classified by:
(1) Grain Size
Coarse: pebbles, cobbles, boulders
Sand (0.0060.2 (cm)
Silt (0.004  (cm)
Clay ( < (cm)
(2) What the mineral composition is
Ex: Limestone is composed of calcite

19. Igneous Rocks

20. Igneous Rocks “from fire”
These rocks form the solidification of molten rock
Magma- molten rock BENEATH the surface
Lava- molten rock that goes above the surface
The Texture mainly depends upon
how fast the molten rock cools
Fast= fine grained; small crystals; smooth
Ex: Rhyolite
Slow=course grained; large crystals; rough
Ex: Granite

21. Igneous Rocks and Texture
Intrusive or “Plutonic” rocks- will have Coarse grains or larger crystals
Extrusive or “Volcanic” rocks- will have fine grains or small crystals

22. Pegmatites
Igneous rocks with extremely coarse texture (large crystals)

23. Glassy Texture/Non Crystalline
When a mineral cools so fast that crystals do not have time to form
Example: Obsidian

24. Vesicular Texture
Some molten rock contains volatiles (gases) trapped inside
When the gas releases, bubble like features are recorded in the rock
this is called “Vesicular Texture”
Ex: Scoria Ex: pumice

25. Igneous Rocks and Composition
Mineral Composition
(1) Felsic- are rocks rich in Al and Si minerals like K-feldspar and quartz and LIGHT in color
Ex: Granite and Rhyolite
(2) Mafic- are rocks rich in Mg and Fe minerals like pyroxene, olivine, & hornblende and are DARK in color

26. Can a rock be neither felsic or mafic?
YES
Igneous rocks like:
Andesite 
Diorite 
Both have roughly the same amounts of mafic and felsic minerals

29. The heat is on! The pressure is on!
Metamorphic Rocks
The heat is on!
The pressure is on!

30. Metamorphism= ↑ T & P
Any existing rock can be metamorphosed with ↑ T & P ex: LimestoneMarble
The “parent rock” becomes recrystallized
↑ the size of crystals/grains
new minerals form

31. Two types of Metamorphism
1.) Contact Metamorphism: rocks come into contact with magma/lava of an instrusion/extrusion
With this supplied heat, rocks metamorphose
*These rocks show no foliation because not much change in P

32. 2.) Regional Metamorphism
Sections of the lithosphere (called plates) converge/collide over long periods of time and 10’s of (km) deep
The rocks at these collision zones are under very high P
These rocks show different texture than contact metamorphic rocks due to high P

33. Textures Foliated- Non-Foliated-
Have layers of crystals formed by recrystallization where minerals “align” under high P (Regional M)
Non-Foliated-
Are NOT layered because they were not subject to high directional P

34. Banding=Extreme Foliation
Extremely high P causes recrystallization to form thick bands of minerals
Example: Gneiss

35. Metamorphic Identification
ShaleSlate (thin foliations, no visible crystals)
↑T & P: Slate Phyllite (shiny surface: has mica )

36. 3.)Phyllite  Schist (higher % mica)
4.)Schist  Gneiss (extreme foliation)

37. Non-foliated identification
Conglomerate  Metaconglomerate

38. *composition* is the key to identification in non-foliated rocks Usually made of one mineral
Marble is metamorphosed Limestone
(calcite) or dolostone so it
will fizz with HCL
Quartzite is metamorphosed
sandstone and will
easily scratch glass
Anthracite Coal is usually
shiny and black