1. Classifying Rocks

2. Figure 3 Texture helps geologists classify rocks
Figure 3 Texture helps geologists classify rocks. Forming Operational Definitions – Looking at the rocks below, describe the characteristics of a rock that help you define what a rock’s “grain” is.

3. Figure 3: Sample Answer Texture is described with the terms based on:
Grain size
Fine-grained
Coarse-grained
Grain shape
Smooth
Jagged
Grain pattern
banded
nonbanded

4. What characteristics are used to identify rocks?
When studying a rock sample, geologists observe the rock’s
Color
Texture
Determine its mineral composition

5. What are the three major groups of rocks?
Igneous rock
Forms from the cooling of molten rock – either magma below the surface or lava at the surface
Sedimentary rock
Forms when particles of other rocks or the remains of plants and animals are pressed and cemented together
Forms below the surface
Metamorphic rock
Forms when an existing rock is changed by heat, pressure, or chemical reactions
Most metamorphic rock forms deep underground

6. What tests do geologists use to identify minerals in rocks?
Scratch Test (Mohs)
Use acid to determine whether the rock contains the mineral calcite
Magnet test

7. Igneous Rock-0rigin
Igneous rocks form when molten rock cools and solidifies. Molten rock is called lava when it is above the Earth’s surface and magma when it is below.

8. Intrusive Igneous Rocks
Igneous rocks that form below the Earth’s surface are called intrusive igneous rocks .
They form when magma enters a pocket or chamber underground that is relatively cool and solidifies into large crystals as it cools very slowly.

9. Intrusive Igneous Rock
EXAMPLES:
1. Granite
2. Gabbro
3. Diorite

10. Intrusive Igneous Rock:
inside the volcano
cools slowly
large crystal
coarse grained

11. Extrusive Igneous Rocks
Extrusive igneous rocks, or volcanic, form when magma makes its way to Earth's surface. The molten rock erupts or flows above the surface as lava, and then cools forming rock.
Most extrusive (volcanic) rocks have small crystals. Examples include basalt, rhyolite, and andesite.

12. Glassy Igneous Rocks
Glassy Igneous Rocks cool so rapidly, that atoms don’t have enough time to get together, bond and form crystals. To cool this quickly the rocks MUST be extrusive.
Pumice (left)
Scoria (bottom left)
Obsidian (bottom)
Note gasses in the lava can cause fine holes as seen in the pumice and scoria.

13. Extrusive rocks: Outside the volcano Cools quickly Small crystal
Fine grained

14. Rock Cycle Questions What are the 3 types of rocks?
Why is the set of natural processes by which rocks change into other types of rocks called a cycle?
If a rock began as a metamorphic rock, what could happen to it?
Draw a diagram showing how an igneous rock could change into a metamorphic rock and how the metamorphic rock could change into a sedimentary rock.

15. Sedimentary Rocks
Rocks made of bits & pieces of other rocks. Sedimentary rock forms when sediments-rocks made of bits and pieces of other rocks are pressed and cemented together, or when minerals form from solutions.

16. How Sedimentary Rocks Form:
When rocks, plants, and loose material get pressed into layers over time.
This process includes:
Erosion-running water, wind, or ice loosen and carry fragments of rock.
Deposition-is the process by which sediment settles out of the water or wind carrying it.
Compaction-particles squeezed together under great pressure.
Cementation- particles are glued together.

17. Types of sedimentary rocks?
There are 3 main types of sedimentary rocks.
1.Rocks from sediments
2.Rocks made from remains of plants and animals. (contains fossils)
3. Rocks made from minerals that are dissolved in solutions

18. What is a metamorphic rock?
The term "metamorphic" means "to change form."
Any rock (igneous, sedimentary, or metamorphic) can become a metamorphic rock. If rocks are buried deep in the Earth at high temperatures and pressures, they form new minerals and textures all without melting. If melting occurs, magma is formed, starting the rock cycle all over again.

19. Metamorphic Rock Types
There are two types of metamorphic rocks.
Each is classified according to its composition and texture.
Foliated
Nonfoliated.

20. Foliated Metamorphic Rocks
FOLIATED metamorphic rocks are those in which the minerals have been flattened and pushed down into parallel layers. The bands in foliated metamorphic rock look like pages in a book.
Examples of foliated rocks are slate, shale, and gneiss.

21. Non-foliated
NON-FOLIATED metamorphic rocks do not display layers. Rather, they are massive structures with no obvious banding. The mineral grains grow and rearrange, but they don’t form layers.
A good example of non-foliated rock is quartzite, the smooth-textured, metamorphosed form of the mineral quartz.
A coarse-textured non-foliated rock is marble.
Anthracite, or hard coal, is a non-foliated rock that forms when intense pressure drives gases out of soft coal, causing it to harden.

22. The Rock Cycle
Sedimentary
Metamorphic
Igneous

23. The Rock Cycle
Rock – a naturally formed solid that is usually made up of one or more types of minerals Rock Cycle – the set of natural processes that form, change, break down, and reform rocks.

24. 3 Rock Types Review
Igneous Rock – forms when molten rock cools and becomes solid. This can happen within earth or on the surface Sedimentary Rock – forms when pieces of older rocks, plants, and other materials get pressed and cemented together Metamorphic Rocks – forms when heat and pressure causes older rocks to change into new types of rocks. These are formed deep under the earth.

26. Describing the Rock Cycle
A rock’s cycle begins by becoming one of the three types of rocks.

27. Describing the Rock Cycle
If it begins as igneous, it can be changed with heat and pressure to become a metamorphic rock or it can reach the surface, be broken down and turn into a sedimentary rock.
If the rock begins as sedimentary, then it can be changed by heat and pressure into a metamorphic rock or it can be broken down into sediment.

28. Describe the Rock Cycle
If the rock begins as a metamorphic rock then it can be turned into magma which eventually becomes an igneous rock or it can be brought up to the surface of earth and broken down into sediment to become a sedimentary rock.

29. Rock Cycle Vocabulary
Erosion – the movement of rock pieces from one place to another by wind, water, or ice
Weathering – the breaking down of rocks by wind, water, ice, or plant roots
Heat – high temperatures
Pressure – caused by layering or weight
Melting – occurs due to magma
Deposition – when rocks are moved to a new location due to erosion

30. Rock Cycle