Transcript Igneous Rocks

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.
1. Magma – hot, molten rock.
2. Lava – magma that reaches earth’s surface.
3. Rate of cooling can be determined by crystal
size.
a. Large crystals – magma cooled
slowly inside earth. Intrusive or
plutonic rocks.
b. 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)
GRANITE
RHYOLITE
a. Felsic rocks – light in color, low in density,
and rich in feldspar and silica.
b. Mafic rocks – dark colored, high in density,
and rich in magnesium and iron.
Questions
1. 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
2. Large crystals in a rock show that the rock
formed by:
3. 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%
5. Which characteristic of an igneous
rock provides the most information
about how it formed?
a) Color b) texture c) streak d) hardness
http://www.eram.k12.ny.us/education/sctemp/190b1c88a4f2b1
9bc1aff975efb87c7c/igneous.swf