Download Igneous Rocks Notes

1. The book says:
After the Earth formed, the planet’s interior became so hot
that magma formed. Lava repeatedly flowed over the
surface and hardened, forming a rocky crust. That crust
sank into Earth’s interior, allowing more lava to erupt over
the surface and harden to form rock.
3. The book says:
Extrusive rock is igneous rock formed from lava that erupted
onto Earth’s surface. Basalt is the most common extrusive
rock. Basalt forms much of the crust, including the oceanic
crust.
Ms. Krupa says:
Ms. Krupa says:
The Earth’s crust is made
out of rock, which came
from magma deep below
the Earth’s surface.
Magma and lava are the
same thing; magma is
INSIDE the earth, lava is
ON the surface.
Extrusive rocks come from
the exterior (outside) of the
Earth. They are made of
lava.
Example: Basalt – makes
up the part of Earth’s crust
sitting under the oceans
2. The book says:
Igneous comes from the Latin word ignis, meaning “fire”
Igneous rocks are classified according to their origin,
texture, and mineral composition
4. The book says:
Igneous rock that formed when magma hardened beneath
the Earth’s surface is called intrusive rock. The most
abundant intrusive rock in the continental crust is granite.
Ms. Krupa says:
Ms. Krupa says:
Igneous rocks are
classified (sorted) by where
they come from, their
texture, and what minerals
they are made of.
Intrusive rocks come from
the interior (inside) of the
Earth. They are made of
magma.
Example: Granite – makes
up the “land” part of Earth’s
crust
5. The book says:
The texture of an igneous rock depends on the size and
shape of its mineral crystals. Rapidly cooling lava forms
fine-grained igneous rocks with small crystals. Slowly
cooling magma forms coarse-grained rocks with large
crystals. Therefore, intrusive and extrusive rocks usually
have different textures.
Ms. Krupa says:
Inside of the Earth, magma
cools slowly, allowing large
crystals to form inside of
intrusive igneous rocks.
On the surface, lava cools
quickly, so smaller crystals
form. Sometimes the lava
cools so fast, that NO
crystals form.
6. The book says:
A rocks mineral composition determines its color
Ms. Krupa says:
The same type of rock can
look different than others of
its kind, depending on what
minerals it is made of.
7. The book says:
People throughout history have used igneous rock for tools
and building materials. The ancient Egyptians used granite
for statues. The Incas of Peru carefully fitted together great
blocks of granite and other igneous rocks to build a fortress
near Cuzco, their capital city. The US used granite in
buildings, bridges, and to pave streets in the 1800s and
early 1900s. Today, thin, polished sheets of granite are
used in curbstones, floors, and kitchen counters. Basalt is
crushed to make gravel that is used in construction. Pumice
is a good abrasive used in cleaning and polishing. Ancient
Native Americans used obsidian to make sharp tools for
cutting and scraping.
Ms. Krupa says:
Igneous rocks have had many uses
throughout history and today. Some
uses are: building materials and tools.
Pumice is an extrusive rock that is very
light and can be ground down and used
in abrasives, cleaners, even pencil
erases and toothpaste. It’s often used
for pedicures to exfoliate dry skin.