Presentation on theme: "Hot rocks/Fire Rocks Igneous comes from Latin and means “fire”."— Presentation transcript:
1Hot rocks/Fire Rocks Igneous comes from Latin and means “fire”. Igneous RocksHot rocks/Fire RocksIgneous comes from Latin and means “fire”.
2Key Questions What is an Igneous Rock? How are Igneous Rocks classified?What are the two types of Igneous rocks?What are the characteristics of Intrusive Igneous Rocks?What are the characteristics of Extrusive Igneous Rocks?What is Volcanic Glass?
3Igneous Rock Igneous rocks form when molten rock cools and solidifies. Molten rock is called magma when it is below the Earth’s surface and lava when it is above.
4when molten rock cools and solidifies Magma (below)Lava (above)
5Igneous Rock classification Igneous rocks are classified two different ways:Where they were formedWhat they are made from (mineral composition)
6Intrusive Igneous Rocks Igneous rocks that form below the Earth’s surface are called intrusive igneous rocks.They form when magma enters a pocket or chamber underground that is relatively cool and solidifies into crystals as it cools very slowly.
7when molten rock cools and solidifies Crystal sizemagmaIntrusiveslowlyMagma (below)when molten rock cools and solidifieslargeLava (above)
8Intrusive Igneous Rock Most intrusive rocks have large, well formed crystals. The mineral crystals within them are large enough to see without a microscope.The more slowly molten rock cools within the Earth, the larger the igneous rocks crystals will be.Examples of intrusive igneous rocks are granite, gabbro and dioriteDiorite
9large Crystal size magma Intrusive slowly Magma (below)when molten rock cools and solidifieslargeLava(above)Granite, gabbro, diorite
10Extrusive Igneous Rocks Extrusive igneous rocks, or volcanics, form when magma makes its way to Earth's surface. The molten rock erupts or flows above the surface as lava, and then cools forming rock.Most extrusive (volcanic) rocks have small crystals. Examples include basalt, rhyolite, and andesite.
11Lava Extrusive Quickly large Crystal size Small or not visible magma Pumice, obsidian, basaltmagmaIntrusiveslowlyMagma (below)when molten rock cools and solidifieslargeLava(above)Granite, gabbro, diorite
12Volcanic GlassPumice, obsidian, and scoria are examples of volcanic glass.These rocks cooled so quickly that few or no mineral grains formed.Most of the atoms in these rocks are not arranged in orderly patterns, and few crystals are present.
13Glassy Igneous RocksGlassy Igneous Rocks cool so rapidly, that atoms don’t have enough time to get together, bond and form crystals. To cool this quickly the rocks MUST be extrusive.Pumice (left)Scoria (bottom left)Obsidian (bottom)Note gasses in the lava can cause fine holes called vesicles as seen in the pumice and scoria.
14ClassificationIgneous Rocks are also classified by their physical and chemical properties.
15Lava Extrusive large Crystal size Quickly magma Intrusive slowly Small or not visiblePhysical & chemical propertiesPumice, obsidian, basaltExtrusivemagmaIntrusiveslowlyMagma (below)when molten rock cools and solidifieslargeLava(above)Granite, gabbro, diorite