Unit 2 Earth Materials Lab 2-3 Igneous Rock Identification

Unit 2: Earth Materials LAB: 2-3 Igneous Rock Identification

Vocabulary:

Igneous: Produced under the conditions involving intense heat.
Intrusive: Igneous rock that forms beneath Earth’s surface.
Extrusive: Igneous rock that forms at the Earth Surface.
Felsic: Igneous rock rich in potassium feldspar and quartz and light color.
Mafic: Igneous rocks that are rich in dark Plagioclase feldspar, pyroxene and that are dark in their color.
Lava: Magma that reaches Earth surface.
Texture: The feel of a rock due to its size, shape and its arrangement of mineral crystal or sediment in a rock.
Porphyry: Igneous rock containing coarse crystals in a finer grained groundmass
Report Sheet 5 | Light | Vesicular | Extrusive | | Felsic | Pumice | 6 | Dark | Glassy | Extrusive | | Felsic | Obsidian | 7 | Light | VeryCoarse | Intrusive | | Felsic | Pegmatite | 8 | Light | Fine | Extrusive | | Felsic | Rhyolite | 9 | Dark | Fine | Extrusive | | Mafic | Basalt | 10 | Dark | Vesicular | Extrusive | | Mafic | VesicularBasalt | 11 | Light | Non-Vesicular | Intrusive | | Felsic | Pegmatite | 12 | Light | Coarse | Intrusive | | Felsic | Granite |

Sample # | Color(Light orDark) | Texture | How Formed( Extrusive OR Intrusive) | MineralsPresent | Composition(Felsic OR Mafic) | RockName | 1 | Dark | Vesicular | Extrusive | Plagioclase Feldspar | Mafic | Scoria | 2 | Light | Coarse | Intrusive | | Felsic | Granite
| 3 | Dark | Coarse | Intrusive | | Mafic | Gabbro | 4 | Light | Coarse | Intrusive | | Felsic | Diorite |

Discussion Questions:

1. The size of the mineral grains affected by the rate in which molten rock material cools is that if an igneous rock has large crystals it takes more time to cool and form crystals, but if the rock have very small crystals or no crystals it cools more quickly. 2. You can determine if an igneous rock has Extrusive or Intrusive origin by observing its visible crystals:
Extrusive the rock has no crystals that are visible or none at all and has air bubbles.
Intrusive rock that has visible crystals 3. The characteristics of a light colored igneous rock differs from a dark colored igneous rock:
Light Colored Rock is most likely to be felsic, and have a lot of aluminum and silicon.
Dark Colored Rock has a lot of magnesium and iron called mafic. 4. The density of a light colored igneous rocks differ from dark color rocks is that lighter color igneous rocks have a lighter density then dark colored igneous rock have a more heavy density. 5. The difference between lava and magma is: Lava is at the surface of the earth (on the ground) Magma is actually lave, but it’s called magma when it reaches earth’s surface and then cools down. 6. A pegmatite texture is very coarse which it has plenty of time to form crystals.

Conclusion Question:

The basic in which igneous rocks are classified are: * Crystal Size (texture) * Color * Method of Formation (Intrusive/Extrusive) * Density * Composition (Mafic/Felsic)