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Igneous Rocks CH 3 Prentice Hall p. 78-81 CH 3 Prentice Hall p. 78-81.

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Presentation on theme: "Igneous Rocks CH 3 Prentice Hall p. 78-81 CH 3 Prentice Hall p. 78-81."— Presentation transcript:

1 Igneous Rocks CH 3 Prentice Hall p CH 3 Prentice Hall p

2 Form from lava or magma Made of mineral crystals Classified according to: – Origin – Texture – Mineral Composition Igneous Rocks

3 Classified according to where they formed. IntrusiveExtrusive Origin of Igneous Rocks

4 Intrusive Forms when magma hardens beneath the Earths surface. Granite Makes up most of the continental crust. Origin of Igneous Rocks

5 Extrusive Forms from lava that erupted onto Earths surface. Basalt Forms much of the ocean crust. Origin of Igneous Rocks

6 A Streak B Origin C Solid D Hardness Which is a way to identify if a rock is Igneous?

7 Igneous Rock Textures Slowly cooling, large crystals Example: Granite Coarse Grained Lava cools quickly Forms smaller crystals. Fine Grained Both textures – large AND small crystals. Cools slowly, then rapidly. Porphyritic Rock cools too quickly for crystals to form. No Crystals

8 A solid in which the atoms are arranged in a pattern that repeats again and again. What is a Crystal?

9 Depends on the size and shape of its mineral crystals. Igneous Rock Textures Coarse Grained PorphyriticFine Grained No Crystals

10 A Coarse-grained B Fine-grained C Porphyritic D No visible crystals In your tray, what is the texture of sample…

11 Most of Earths rocks contain silica (silicon dioxide, SiO 2 ) Mineral Composition High Silica (Felsic) Forms light colored rocks. Granite Dark to light gray, red and pink. Low Silica (Mafic) Forms dark colored rocks. Basalt Contains dark colored minerals. No quartz.

12 Igneous Rock Chart Origin Intrusive (Magma) Coarse Grained Granite Continental Crust Gabbro Both Porphyritic Large crystals with small crystals Scattered on top. Extrusive (Lava) Fine - Grained Rhyolite Basalt Ocean Crust No Crystals PumiceObsidian Low Density High Felsic (High) Silica Mafic (low)

13 ABC Which rock likely has the most silica?

14 Granite - building materials Obsidian - sharp tools Basalt - gravel, construction Pumice - used for cleaning and polishing Uses of Igneous Rocks Igneous rocks are useful because they are hard, durable and dense

15 Class Work Examine 5 Igneous Rocks and write down their texture – (Fine-grain, Coarse-grain, Porphyritic, No Grain) Read the textbook, pages – Answer Questions 1 – 4 on page

16 Silica Content Felsic Felsic – Granite – Rhyolite Mafic Mafic – Basalt – Gabbro Intermediate Intermediate – Diorite – Andesite

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