Warm Up 1.What is the purpose of the currents? 2.What are the 3 different types of rocks? 3.How do you create each type of rock?

Minerals & Rocks IGNEOUS ROCKS =aCnAF1Opt8M

Igneous rocks are classified two ways 1.By the way they are formed 2.Their mineral composition and color Lava is molten material on Earth’s surface. Igneous rocks Formed from the crystallization of magma or lava

Extrusive = form above Earth’s surface are fine-grained and cool quickly Intrusive = form below Earth’s surface are coarse-grained and cool slowly

Fine grained (extrusive)

Coarse grained (intrusive)

Igneous Rocks Mineral Classification –Felsic light-colored igneous rocks and have high silica contents. –Mafic dark-colored igneous, have lower silica contents, and are rich in iron and magnesium. –Intermediate- are between Felsic and Mafic –Ultramafic- Very low silica content and high levels of iron and magnesium

The three main groups of igneous rocks are felsic, mafic and intermediate. They are each classified by their mineral compositions. An example of a felsic rock is granite. An example of a mafic rock is basalt. An example of a intermediate rock is andesite.

Ultramafic- Very low silica content and high levels of iron and magnesium Grain Size/Cooling Rates p. 109 When lava flows onto the Earth’s surface it is exposed to air and moisture. Under these conditions, the lava cools quickly and there is not enough time for crystals to form. Therefore, extrusive igneous rocks such as obsidian have no visible mineral grains.

Cleavage- in structural geology and petrology, describes a type of planar rock feature that develops as a result of deformation and metamorphismstructural geologypetrologymetamorphism

Texture Mineral grains can have interlocking edges because different cooling rates. Well-shaped crystals can form during cooling. When this happens, porphyritic texture occur. Rocks with a porphyritic texture can form when crystals of two different sizes form together. This could happen because of slow cooling magma began cooling rapidly.

porphyritic

Igneous Rocks as Resources Igneous rocks have several characteristics that make them especially useful as building materials. –The interlocking grain textures of igneous rocks help to give them strength. –Many of the minerals found in igneous rocks are resistant to weathering.

Ore Deposits Ores are minerals that contain a useful substance that can be mined for a profit. Valuable ore deposits are often found within igneous rocks. –Ores are removed by underground mining or from large, open-pit mines. –If the cost of separating the waste material becomes higher than the value of the ore itself, then the mineral will no longer be classified as an ore **Found in cracks or veins