Aim: What are Igneous Rocks

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Aim What are Igneous Rocks?
I. Rocks made up of more than one mineral.
Rocks are classified according to how they were
formed. Igneous, sedimentary, metamorphic.
A. Igneous rocks that form from magma (lava)
when it cools and hardens.

• Magma hot, molten rock.
• Lava magma that reaches earths surface.
• 3. Rate of cooling can be determined by crystal
  size.

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• Large crystals magma cooled slowly inside
  earth. Intrusive or plutonic rocks.
• Small crystals lava cools quickly on surface of
  earth. Extrusive or volcanic rocks.

4. Igneous rocks are classified according to
crystal size and color. (go to page 6 of
Reference Tables)
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GRANITE
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RHYOLITE
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• Felsic rocks light in color, low in density,
  and rich in feldspar and silica.
• Mafic rocks dark colored, high in density, and
  rich in magnesium and iron.

Questions

• According to the E.S.R.T.s, which of these is a
  fine-grained, dark colored igneous rock? a)
  basalt b) diorite c) shale d) granite
• Large crystals in a rock show that the rock
  formed by

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• Sand collected from a beach contains a mixture of
  pyroxene, olivine, hornblende, and plagioclase
  feldspar. According to the E.S.R.T.s, what can
  we conclude about the rock that it came from?
• a) it was mafic in composition b) it was
  relatively low in density c) it contained only
  light-colored minerals d) it was either granite
  or rhyolite.
• 4. According to the E.S.R.T.s, what is the
  approximate percentage of plagioclase feldspar in
  igneous diorite? a) 10 b) 30 c) 60 d) 90

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5. Which characteristic of an igneous rock
provides the most information about how it formed?
a) Color b) texture c) streak d) hardness
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Turn to Page 6 ESRT!!!
http//www.eram.k12.ny.us/education/sctemp/190b1c8
8a4f2b19bc1aff975efb87c7c/igneous.swf