IV. 3 Rock Categories

A. Igneous1. Origin

2. Texturea. Depends on size/shape of mineral crystalb. Intrusive – larger crystals (coarse-grained)c. Extrusive – smaller (if any) crystals (fine-grained)d. Porphyritic Texture (combo of two)

Intrusive Extrusive

Igneous rock that formed when magma hardened beneath Earth’s surfaceEx. Granite

Igneous rock formed from lava that erupted onto Earth’s surfaceEx. Basalt

IV. 3 Rock Categories

3. Mineral Compositiona. Silica (Material that is a combination of Oxygen and

Silicon)i. Low-Silica Lava = dark-colored rocks (like Basalt)ii. High-Silica Magma = light-colored rocks (like Granite)

HOMEWORK

• Read Chapter 3, Section 2 (pages 78-81)• Index Cards for bold vocabulary words found

in Section 2• Section 2 Review, # 2, 4, 5

Igneous RocksWhere can we find these rocks in our everyday lives?

Granite Slabs and Stones Used in the Kitchen

Granite in ArchitectureThis is a sample of granite architecture found in Aberdeen, Scotland. Granite is a very durable, strong rock used in buildings, statues, monuments, and structures throughout the world.

Granite is commonly used in the kitchen not only for its beautiful colors and patterns but also because it can withstand extreme temperatures. You can cook food on granite to enhance the flavor of certain meals.

Primp and Perm with PumiceAn igneous-volcanic rock, pumice is a porous, brittle variety of rhyolite and is lightenough to float. It is formed when magma of granite composition erupts at the earth’s surfaceor intrudes the crust at shallow depths. It is used as an abrasive material in hand soaps,emery boards, etc.

Gabbro Quarries Used to make Paving StonesGabbro is a durable igneous rock that is commonly found in paving aggregates. Roads and architectural features can be made from Gabbro.

Materials for Hot Rock TherapyThis type of therapy requires stones that preserve warmth. Basalt stones are particularly common and can be heated as high as 140 degrees.

Basalt Stones For MassagesBasalt stones are very popular products for use in massage. Formed from volcanic rock known for its smooth texture, basalt rocks are particularly amenable to high temperatures. When heated, these stones retain their warmth for long periods of time and are therefore ideal for stone therapy.

Igneous Rocks Used for CookingSeveral older Char-Broil gas grill models incorporated lava rocks near the grill burners to help distribute heat from gas-fed flames evenly throughout the grilling chamber. Lava rocks retain heat, making grilling more efficient. The rocks are heated by the gas flame and cook like charcoal.

Lava rock heats quickly and disperses the heat to the interior of the grill. Lava is porous and allows grease to accumulate, lessening its efficiency and increasing flare-ups. Replace lava rock yearly or turn over to expose a fresh surface.

Didn’t that Blow Your Mind?!