3-2 igneous rocks form from molten rock

Intrusive has the prefix in meaning inside and intrusive rock is formed within earths surface. Extrusive has the prefix ex meaning outside of and extrusive rock is formed outside of the earth on the surface.

What are the names extrusive and intrusive appropriate for the two types of igneous rock?

Basalt and gabbro have the same composition and are made/formed in the ocean. Gabbro is made under the surface from magma, and basalt is made above the surface from the same type of lava.

Compare and contrast basalt and gabbro?

Granite and pumice are made of the same composition of molten rock, but granite is under the surface when it cools and pumice is what it becomes if it cools above the surface.

Compare and contrast granite and pumice?

After identifying the texture of an igneous rock, geologist classify the rock on the basis of how rich it is in silica.

Geologist first use texture to classify the rock, after that they classify them by what?

Intrusive

Cooling rate and why: high temps; allows magma to cool slowly.

Extrusive

Cooling rate and why: lower temps; causes lava to cool quickly.

Igneous rock with high levels of silica such as granite and rhyolite, are typically light in color. Those with low levels of silica such as gabbro, and basalt, are typically dark in color.

Explain how silica can affect the color of the rock? Both examples.

Surface; within

Extrusive rocks are at the Earths And intrusive rocks form Earth.

Mount St. Helena a volcano with silica rich lava. This lava doesn't flow easily, so it builds up cone shaped volcanoes with steep sides. Lava flows add a new extrusive igneous rock to Mount Saint Helena, so it will grow taller.

Give an example of extrusive rock formation that is high in silica? Explain the way it was made?

The Hawaiian islands are a chain of volcanoes that are built of basalt lava, which is low in silica. This lava arrives at a single point and build up a huge volcano with gently sloping sides, because it spreads easily. The Hawaiian volcanoes started erupting underwater in over a long period of time they grew tall enough to rise above the surface as islands.

Give an example of extrusive rock formation that is low in silica? explain the way it was made?

Ship rock is in intrusive rock formation that was originally formed below the surface, 30 million years ago. The formation is made of magma that once fed a volcano. The magma cools slowly to create large crystals. The intrusive igneous rock is harder, so it lasted longer, while the weaker rock was worn away by wind and water. The worn away rock reveals the intrusive rock formation, such as ship rock.

Give an example of intrusive rock formation? How was it made? What was the crystal size? Why has it lasted so long?

Peoples decisions about how to use igneous rocks are based in part on the rocks crystal sizes. For example, rock with large mineral crystals are often used as building stones because they are attractive. They are used for building and jewelry.

How and why do people use igneous rock?

An igneous rock is classified on the basis of its minerals composition and the size of its mineral crystals.

How are rocks classified? Two ways

Intrusive rocks reach the earth surface because forces inside them can push rocks up, as when mountains form. Also, water and winter break apart and carry away surface rocks. Then deeper rocks are uncovered at the surface.

How do you intrusive rocks reach the surface?

Some igneous rocks contain crystals of very different sizes. These rocks formed from magma that started cooling within earth and then erupted onto the surface. The large crystals grew as the magma cooled slowly. The small crystals grew as the lava cooled quickly.

How does an igneous rock that has both large and small minerals crystal form?

Extrusive

How does the rock form: lava cools (on surface).

Intrusive

How does the rock form: magma cools (in earth).

A rock formed from magma can have the same composition as a rock form from lava. The rocks, though, will have different names, because the sizes of their crystals will be very different. One may be extrusive and the other is intrusive.

If two igneous rock have the same composition, one was made from lava and the other magma - how can they be name differently?

It's built of extrusive rock because it is formed above the surface by lava, then it kept building around and spreading.

Is the volcano in the illustration built of the layers of intrusive or extrusive of igneous rock? Explain your answer?

Silicate minerals

Most minerals are made of what.

Extrusive

Size of crystal: since lava cools quickly there is no time for large mineral crystals to form. They are small; or there are no crystals.

Intrusive

Size of crystal: slow cooling allows time for large mineral crystals to grow.

Intrusive

Temp were it forms: the interior of the earth is very hot.

Extrusive

Temp were it forms: the surface of the earth is cooler than earths interior.

Intrusive

The most common rock: granite

Extrusive

The most common rock: pumice

Igneous rocks form from molten rock, but where does it come from? The temperature inside earth increases with depth. That is, the farther down you go, the hotter it gets. Deep within earth, temperatures are not hot enough -750°C to 1250°C about (1400°F to 2300 degrees Fahrenheit) -to melt rock. This molten rock is called magma. Molten rock that reaches earth surface is called lava.

What forms igneous rocks? Where does the material come from?

Molten rock that reaches earth surface is called lava. Molten rock under the earths surface is magma .

What is the difference between lava and magma?

Extrusive

Where does the rock cool: on the surface

Intrusive

Where does the rock cool: within earth

Intrusive

Where is the rock usually found on earth: inside a volcano

Extrusive

Where is the rock usually found on earth: ocean floor, outside volcano

They are made mainly of these, because they are the most common group of minerals in the earths crust, and that's where igneous rocks are formed.

Why are they made of these?

I would expect it to be light in color, because the rock will be high in silica, making it lighter. It will be high in silica, because that type of lava makes a volcano more explosive. It's more explosive, because the magma is thick and sticky, so pressure builds up before it explodes.

Would you expect extrusive rock produced by an explosive volcano to be light or dark in color? Why?