Station One-Basalt
(Write this description on your lab sheet)
Basalt is one of the most common volcanic rocks. It is usually
grey to black in color and fine-grained due to rapid cooling of the
very fluid lava on the surface. Basalt is the principal rock of the
ocean floor and is made up of feldspar and pyroxene.
1.
Use the hand-lens to carefully look at this sample. Are you able to
see any crystals? If so, describe them.
2.
Using “at least” three adjective, describe the texture of this
sample.
Station Two- Vesicular Basalt
(Write this on your lab sheet)
This specimen of Aye Aye lava is from Hawaii. This rock gets it’s
name from the sharp points throughout it’s outer covering. When
people walk barefoot on this rock they often yell “Aye! Aye!”
1.
Describe how this rock MIGHT have cooled to form it’s sharp points.
2.
Look at the air bubbles in this sample. Do you think this rock cooled
quickly or slowly? Explain your reasoning.
Station Three- Andesite
(
Write this on your lab sheet)
This igneous rock is a fine-grain rock that forms from
lava flows from andesitic volcanoes. Andesitic
volcanoes are often associated with subduction zones.
1.
Use the loop to look at the crystals, then use the metric
ruler to measure, in millimeters, the size of the largest
crystal you can see.
2.
Do you think this rock cooled quickly or slowly? Explain
your thinking…
Station Four-Obsidian
(
Write this on your lab sheet)
Obsidian is a naturally occurring volcanic glass formed a silica-rich
volcanic rock. It is produced when lava, extruded from a volcano,
cools quickly without crystal growth. Obsidian breaks with a very
sharp fracture, which made it good for making cutting tools
1. Describe how this igneous rock is different from other types.
2. Describe the texture of the Obsidian?
Station Five- Hornblende Granite
(Write this on your lab sheet)
This igneous rock is coarse-grained, with equal-sized
crystals, giving it an even texture. Hornsblende Granite
is made up of Quartz, Feldspar, and Mica.
1. Do you think this rock formed quickly or slowly? Would it
be called intrusive or extrusive?
2. Do you think this rock cooled quickly or slowly? Explain
your reasoning.
Station Six-Granite
(Write this on your lab sheet)
Here are 2 specimens of Granite. Granite is the commonest of all
intrusive igneous rocks. It can contain a variety of different
minerals like Quartz, Feldspar, Mica, and Hornsblende.
1. Describe the similarities and differences between these two
specimens.
2.
Are the crystals in each specimen the same size? What does that
tell you about these specimens?
Station Seven-Scoria
(Write this description in your Rock book)
Scoria is a dark-colored, vesicular, extrusive igneous rock. The
vesicles are a result of trapped gas within the melt at the time of
solidification. It often forms as a frothy crust on the top of a lava
flow or as material ejected from a volcanic vent and solidifying
while airborne.
1.
This volcanic rock appears to have various tan flecks within the
black. Take a guess, how do you think it formed?
2.
Describe the feel of this rock.
Station Eight-Pumice
(Write this description in your Rock book.)
Pumice is a light-colored vesicular igneous rock. It forms through
very rapid solidification of a melt. The vesicular texture is a result
of gas trapped in the melt at the time of solidification. Place the
pumice in the container of water.
1. Does this type of ROCK float or sink? Test it.
2.
Study the texture and composition of this rock. Note all of the air
bubbles that were present when this was a liquid are now just
empty holes in the rock. Do you think this rock cooled quickly or
slowing? Explain your thinking