Station One-Basalt

1
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.
• Use the hand-lens to carefully look at this
  sample. Are you able to see any crystals? If so,
  describe them.
• Using at least three adjective, describe the
  texture of this sample.

2
Station Two- Vesicular Basalt

• (Write this on your lab sheet)
• This specimen of Aye Aye lava is from Hawaii.
  This rock gets its name from the sharp points
  throughout its outer covering. When people walk
  barefoot on this rock they often yell Aye! Aye!
• Describe how this rock MIGHT have cooled to form
  its sharp points.
• 2. Look at the air bubbles in this sample.
  Do you think this rock cooled quickly or slowly?
  Explain your reasoning.

3
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.
• 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.
• Do you think this rock cooled quickly or slowly?
  Explain your thinking

4
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?

5
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.

6
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.
• Are the crystals in each specimen the same size?
  What does that tell you about these specimens?

7
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.
• This volcanic rock appears to have various tan
  flecks within the black. Take a guess, how do
  you think it formed?
• Describe the feel of this rock.

8
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.
• 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