1. Monroe Pictures by Raquel
Rocks and Rock Types
Monroe
Pictures by Raquel

2. Igneous (means “from fire”)
Intrusive ~ Which means that it never
broke through the Earth’s surface
1. Cooled slowly, so large crystals could grow
2. Texture is often rough
3. Crystals can be of different sizes and colors
4. Granite is a good example of a Felsic (light colored) igneous rock.

3. Granite
Pinkish, large crystals, igneous, intrusive

4. Granite (pegmatic)
Pinkish, large crystals, flattened, igneous, intrusive

5. Andesite
Looks like grey granite, igneous, intrusive, from Andes mountain ranges

7. Diorite
Blackish with large crystals, rough, igneous, intrusive, sometimes called black granite.

8. Extrusive ~ Which means that it came out onto the surface of the Earth
Obsidian or basalt are good examples of Mafic (dark colored) rock types

9. Rose quartz
Looks a lot like glass, no crystals seen, often sharp edges, igneous intrusive.

10. Basalt
Very small crystals, black, very dense, makes up the sea floor, igneous, can be intrusive or extrusive.

13. Batholith ~ covers 100’s of square kilometers
Stock ~ covers less than 100 square kilometers
Laccolith ~ “lake of rock”. It may push up hills. Black Hills have a laccolith under them
Sill ~ a sheet of magma between rock layers
Dike ~ a magma flow between rock layers, usually along faults
Volcanic neck ~ central vent of a volcano
Lava Plateau ~ layer of lava

14. Devil’s tower, pre-emergent
Devil’s tower, pre-emergent. Note the tilting of the rocks around the plume, and the igneous core.

15. Devil’s tower, after erosion has removed the surrounding sedimentary soil. Note that the igneous core is still standing, because it will erode more slowly than the surrounding sedimentary soil.

16. Climbing man

17. SEDIMENTARY

18. Sedimentary Chemical

19. Geode
This is a geode that is entirely filled with amethyst

20. Calcium carbonate crystal
Made by drippings of mineral saturated water, sedimentary, chemical.

21. Limestone
Feels “chalky”, sedimentary, chemical. No crystals.

22. Amethyst crystals
Note 6-sided crystals, sedimentary crystals.

23. Sedimentary Clastic

24. Conglomerate
Made of quartz, random sizes and shapes of particles. Much like large sandstone.

25. Sandstone
Made of sand, cemented together with heat and pressure.

26. Sedimentary Organic

27. Bituminous Coal
Came from swamps, is kind of “dirty”, and will metamorphose into anthocitic coal.

29. Coquina
Limestone made from shells of living animals. Looks a lot like oatmeal.

30. Metamorphic

31. Anthracite
Coal that has come from bituminous coal, changes by the metamorphism of heat, pressure and chemical change.

33. Talc
Really soft and smooth, is made into baby powder.

34. Mica-Shist
Very distinct layering in places

35. Breccias
Large pebbles that have been “smooched” together with great heat, pressure and chemical changes

37. Mica (biotite)
Layers peel like paper, extremely thin and “see through”

38. Gneiss
Soft metamorphic rock, under the heads at Mr. Rushmore