1. Common Rocks Lab # 3
1st part of Experiment # 2

2. By the end of the lab we will be able to:
Examine a rock sample and determine if it is a sedimentary, metamorphic, or igneous rock.
Define the terms used to describe the textures of the different sedimentary metamorphic or igneous rock.
Name the common minerals found in most common types of sedimentary metamorphic or igneous rock.
Use a classification key to identify rocks.
Recognize and name some of the common rocks.

3. Rocks and Rock Cycle Rocks - most are made up of mixtures of minerals.
Some are made up of primarily one mineral.
Ex limestone is made up primarily made-up of calcite.
Rock cycle - The process that transforms one rock type into another.

4. Rocks
Igneous
Sedimentary
Metamorphic

5. Igneous Form either underground or above ground.
Underground - they form when molten rock, called magma, deep within the earth becomes trapped in small pockets.
Aboveground they form when volcanoes erupt, causing magma to rise above the earth's surface.

6. Igneous As these pockets of magma cools, it becomes igneous rocks.
Molten rock below ground is magma and above ground is called lava.

7. Sedimentary Rocks
Little pieces of our earth have broken down and worn away.
How? - They are eroded down by wind and water.
These little bits of our earth are washed downstream where they settle.
Layer after layer are pressed together until the bottom layers slowly turn into rock.

8. Metamorphic Rocks
They have "morphed" into another kind of rock.
These rocks were once igneous or sedimentary rocks.
They are under tons and tons of pressure, which fosters a build up of heat; this causes them to change.

9. Rock Cycle

10. Texture Vs. Composition
We can identify types of rocks by describing their texture and composition.
Texture - not how it feels but its cooling history.
Composition - what type of minerals are present.

11. Types of Texture
Coarse Grained
Fine Grained
Porphyritic
Glassy

12. Coarse Grained
The longer the cooling time, the coarser (larger) the crystals present.
This occurs inside the Earth.
Coarse crystals can be seen without a microscope.

13. Fine Grained
This occurs when the the rock is cooled rapidly. The shorter the cooling time the (finer) the crystals will be.
This occurs near or on the Earth’s surface.
Fine crystals can not be seen without a microscope.

14. Porphyritic
Two different size crystals thus different rates of cooling.
This occurs when the rock is cooling, it is pushed upwards where the rock cools faster.

15. Glassy No crystals develop because of very rapid cooling.
Lack of crystals causes the rock to have a glassy appearance.
Can also be a frothy color.

16. Color
Mineral composition is the cause of the color change. We will only talk about
Light
Intermediate
Dark

17. Types of Feldspar
Potassium feldspar - contains potassium, pink in color.
Also called Kspar from Potassium (K) Silicate (s) and feldspar (par) thus Kspar
Plagioclase feldspar – will contain either sodium, calcium or a mixture of both.

18. Chart on pg 26
From left to right the color and concentration of iron and magnesium increases.
As we travel left to right the silica concentration decreases, and the magnesium concentration increases.

19. Light Color In the Felisic group Contains 0-15% dark minerals
Contains potassium feldspar
High concentration of potassium approximately 60-80%
They will have a pink color.

20. Intermediate Color Mixture of light and dark colored minerals.
Contains 15-45% dark minerals.
Contains a percentage of plagioclase feldspar.
Also called andesitic because they were first found in the Andes mountains.

21. Dark Color Contains 45-85% dark minerals
Contains Iron and Magnesium compounds.
High concentrations of Olivine, Pyroxene, and Amphibole.
Also called Feromags.
Fe-iron, mag - magnesium

22. Work to be completed: Complete Chart on pg 27 using chart on pg 26.
Start chapter Summary pg 35 questions 1-10
Do not turn work in; it will be collected next week when we complete the second half of this lab.