Download igneous rocks activity

Name ________________________________
Period __________
Igneous Rocks Activity
(and NOTES)
How are igneous rocks made?
On the diagram to the right (from the ESRT), find the box
that says “Igneous Rock”. With a colored pencil or
highlighter, trace the paths of arrows that lead from
Sedimentary, Metamorphic or Igneous Rock back to the
“Igneous Rock” box. Use this to fill in the information
below.
KNOW&DO: An igneous rock is made when a
_________________, _______________________, or
___________________ rock are ________________ and
turned into ____________. This magma then goes
through the process of ________________________ to
become a new ______________ rock.
Is magma a liquid or solid?
ESRT page 6
What is the difference between lava and magma?
What do you think solidification means?
KNOW:Where solidification occurs (inside or outside of the crust) will determine the texture (crystal size) of
the igneous rock.
In what type of environment would rocks be melted to form magma? Include a type of plate boundary in your
answer.
*Check the answers above with your teacher*
How are igneous rocks named/classified?
KNOW: By two characteristics: mineral composition (identified mostly by color) and texture (crystal
size).
DO: Determining Mineral Composition-mafic or felsic?
The picture below is from part of the Igneous Rock Chart on page 6 of your reference tables. According to this,
list three characteristics of mafic and three characteristics of felsic rocks.
Felsic rocks are:
Mafic rocks are:
______ in color
_______ density
_________ composition
______ in color
_______ density
_________ composition
Below is a little more of the same chart from the reference tables, based on the colors of the minerals given in
the chart, would a salmon (pink) colored rock be considered mafic or felsic and why?
Now look at the sample A on your desk, do you think it is mafic or felsic? Why?
How would you describe the color of a rock that was made from the minerals that aren’t in the two rounded
rectangles above?
Determining Texture (crystal size)
KNOW: The size of the crystals is a direct result of where and how quickly the lava/magma solidified (cooled to
a solid).
Below is yet another part of the igneous chart from ESRT page 6. Use this part of the chart to answer the
questions below.
WHAT TO DO:
-Look on the left side of the chart at the two environments of formation. Fill those two names in the rectangles under
environment of formation below, then look up the definition of each in your workbook and label which one means
inside and which one means outside the crust. Label “inside” and “outside” in the rectangles below as well.
-Based on where the rocks formed, label in the stars, the words lava or magma.
-Your workbook will also tell you, in these definitions, whether rocks in these environments cooled quickly or slowly. Put
the words quickly or slowly in the ovals under the correct environment this would happen in.
-Looking back up at the diagram above, follow the extrusive row over to the column that says crystal size. Compare this
size with a ruler to determine if these would be small, hardly visible crystals or large, easily visible crystals. Label “large
crystals” or “small crystals” in the rounded rectangles below.
Environment of Formation
form
that
cooled
that
cooled
and made
from
form
from
Resulting crystal size
(texture)
and made
Based on the information you filled in above, use your ruler to determine if your sample A is intrusive or
extrusive. Why do you think so? (Check your answer with your teacher.)
Now look at your sample B. It has a special texture called vesicular. Based on what your sample B looks like,
what do you think vesicular means?
Use the “Environment of Formation” section of the Igneous
Rock chart on ESRT page 6 to determine where vesicular
rocks form and label that with a “B” on the picture to the
right.
Would a vesicular rock cool quickly or slowly?
Using your ESRT and observations of color (mineral composition) and texture (crystal size), determine the
name of your rock sample A and B. The names of the rocks on the Igneous Rock chart on page 6 are those that
are in bold in the top part of the chart. To determine what minerals the rock is made of, once you find the
name, follow that section down to the bottom of the chart. All of the patterns in that section can be part of
that rock. (See picture below for help.)
Sample A: ____________________________
made of these minerals:
Sample B: ____________________________
made of these minerals:
*Check your answers with your teacher*
Example: Diorite would
have the minerals in the
rounded rectangle
When demonstrating volcanic eruptions, Mrs. Kent talked about Mt. St. Helens being a very explosive eruption
because the magma that supplied the volcano was very viscous and had a lot of dissolved gases. The more
silica there is in the magma, the more viscous it is. Based on this information, describe what a rock formed
the last time Mt. St. Helens erupted would look like (color, composition, texture). Use your ESRT to help!
Use your ESRT to figure out what mineral or minerals the igneous rock Dunite would be made of and describe
what it might look like.
Could rhyolite and granite be made of the exact same minerals? Why or why not? (Use your ESRT for crying
out loud!)
Suppose rhyolite and granite were made of the same exact minerals, what would make them look different
and therefore be called two different things? (Yep, you guessed it, refer to your ESRT!)
*Check your answers with your teacher PLEASE!*