Download MEET SOME ROCKS AND MINERALS

IGNEOUS ROCKS
Heat from the interior of the earth can make rock hot enough to melt.
Molten (melted) rock that is inside the earth is called magma. If magma is
pushed to the surface where we can see it, we then call the molten rock
lava. Remember that particles of a liquid can roam around freely because
they are not bonded to each other to form a definite shape.
When magma or lava cools, the atoms begin to stick to each other to form
solid chunks. Sometimes this happens v-e-r-y s-lo-w-l-y. Magma deep
inside the earth can cool and solidify over a period of hundreds or even
thousands of years! Slow cooling can give individual atoms time to “line up”
and form definite patterns called crystalline structures. This allows large,
beautiful crystals to form. Granite is an example of a rock with large
crystals that grew slowly because of slow, steady cooling.
When molten rock—particularly lava—cools quickly (like when volcanic
pahoehoe lava cools when it touches ocean water), the atoms “freeze” into
place without having time to “line up” and form large crystals. The solids
that form may have small crystals or even no crystals at all. If there is no
definite pattern to how the atoms link together, the result is an amorphous
solid. Obsidian—a glassy volcanic material—is an example of a rock that is
amorphous.
Choose the best ending for this sentence: Igneous rocks are formed in a
way that is similar to the formation of ______________________ .
A. Rice Krispy bars
C. chocolate bars
B. a milkshake
D. tortillas
Look at the Box of Rocks. Remove and examine the rocks that are labeled
“1” through “6.” These are all igneous rocks—rocks that formed from
cooling magma or lava. On the back of this page, arrange the six igneous
rocks into their correct spots in the table.
IGNEOUS ROCKS (#1-6)
NAME
OBSIDIAN
(ob-SIH-dee-un)
BASALT
(buh-SAULT)
GABBRO
(GA-broe)
GRANITE
(GRA-nitt)
PORPHYRY
(PORR-furr-ree)
PUMICE
(PUH-miss)
DESCRIPTION
Black, shiny and glassy, the sharp
edges can cut (Be careful!)/
Strange “shell-shaped” surfaces
where it has been broken up.
Obsidian is made by quick-cooling
lava. There was not enough time
for the atoms to “line up” neatly
and form large crystals.
Dark gray (almost black), dull, tiny
crystals, dense, no air pockets,
made by cooling lava. Crystals
could grow, but they did not get
large. Much of the oceanic crust is
basalt, formed at mid-ocean ridges.
Mostly dark, large shiny crystals,
dense, no air spaces. Chemically
similar to basalt, but gabbro has
larger crystals because it is made
by slower-cooling magma. Much of
the oceanic crust is gabbro, formed
at mid-ocean ridges.
Black and white “salt and pepper”,
large crystals, dense, no air spaces.
Like gabbro, granite is formed from
cooling magma, but the magma is
chemically different, leading to the
formation of lighter-colored
mineral crystals such as quartz and
pink or white feldspars.
A few big crystals surrounded by
many crystals that are much
smaller. This was magma that at
first cooled slowly (making large
crystals), and then more quickly
(making the smaller crystals).
Nearly white, dull “chalky” look,
cannot see individual crystals, very
low density due to millions of tiny
air pockets. Made by lava shot out
of volcanoes. The gas bubbles
formed before the lava could
solidify. Pumice can float on water!
PUT IT HERE!
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SEDIMENTARY ROCKS
Wind, water, ice, sunlight and gravity all cause rock to weather into smaller pieces.
Through the process of erosion, these rock and mineral pieces, called sediments, are
moved from one place to another. Eventually, the sediment is deposited in layers.
As the new layers of sediment are deposited, they cover older layers. Older layers
become squeezed and compacted (squeezed) by all the weight of the sediments on
top. Dissolved minerals in the ground water can act as “glue” and cement the pieces
of sediment together. The result is a new rock that is made out of the sediments of
older rocks (or even broken seashells!). This new substance is a sedimentary rock.
Sandstone is a sedimentary rock that formed when pieces of sand were cemented
together. Limestone is a sedimentary rock that formed when pieces of seashell
were cemented together.
Coal is also a sedimentary rock, but it is not made out of smaller rock pieces. Coal is
actually made out of the compacted remains of dead swamp plants and animals. As
the layers of dead material build up, pressure changes the material into coal. Such
rocks are called organic because they are made from the carbon-containing bodies
of creatures that used to be alive.
Fossils are traces of ancient organisms that that have been preserved in rock.
Fossils can tell us about bones, leaves, or even animal tracks from long ago. Because
of the way fossils form, they are only preserved in sedimentary rocks.
There is one more way that sedimentary rocks can form. Sometimes water
containing a lot of dissolved mineral atoms will evaporate. When evaporation occurs,
water molecules jump into the air and leave the mineral atoms behind. The mineral
atoms begin sticking to each other to form crystals. Table salt (NaCl) is a
sedimentary rock that formed when sea water evaporated and left atoms of sodium
and chlorine behind.
Choose the best ending for this sentence: Many sedimentary rocks are formed in a
way that is similar to the formation of _________________ .
A. Rice Krispy bars
C. chocolate bars
B. a milkshake
D. tortillas
Look at the Box of Rocks. Remove and examine the rocks that are labeled “7”
through “11.” These are all sedimentary rocks. On the back of this page, arrange
the five sedimentary rocks into their correct spots in the table.
SEDIMENTARY ROCKS (#7-11)
NAME
DESCRIPTION
SHALE
Dark, fine-grained, formed by
layers of mud or clay (i.e.
mixtures of tiny rock particles
and water) that were pressed
together for millions of years.
SANDSTONE
Light colored, sometimes in
layers, feels like sandpaper
and bits of sand can be rubbed
off (Don’t overdo it!). Made by
sand particles (often quartz)
that have been pressed and
stuck together (like how Rice
Crispy bars are made).
LIMESTONE
Tan, dull, fine-grained,
“chalky” surface. Limestone is
mostly made of the mineral
calcite. It was made from
ocean sediments (usually sea
shells) that piled up, got
crushed and stuck together.
A rock made of older pebbles,
gravel, sand and clay. The
individual pieces of sediment
have a rounded appearance
because they were worn
smooth in river beds.
CONGLOMERATE
(conn-GLOMM-ur-ett)
COAL
Black, partly shiny, and low
density. Usually in layers.
Sometimes dead plants and
animals do not get recycled
back into living material. Coal
forms from the remains of
swamp plants buried under
water. As the layers of dead
material build up, pressure
changes the organic material
into coal.
PUT IT HERE!
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METAMORPHIC ROCKS
When a tadpole changes into a frog, or when a caterpillar changes into a
moth or butterfly, this process of change is called metamorphosis. “Meta”
means change and “morph” means form, so a metamorphosis is a “change of
form.”
Rocks can also undergo metamorphosis. This can happen when rocks are
squeezed and/or heated enough to make them almost—but not quite—liquid.
Under great heat and/or pressure, the individual atoms of the rock may
migrate (move) a short distance; this happens very slowly. Then the atoms
combine in new ways. This change is called recrystallization. The result is
a metamorphic rock—a rock that has changed in structure due to heat and
pressure (but without actually melting).
Choose the best ending for this sentence: Many metamorphic rocks are
formed in a way that is similar to the formation of _________________ .
A. Rice Krispy bars
C. chocolate bars
B. a milkshake
D. tortillas
Look at the Box of Rocks. Remove and examine the rocks that are labeled
“12” through “16.” These are all metamorphic rocks. On the back of this
page, arrange the five metamorphic rocks into their correct spots in the
table. When you do so, compare them with the rocks that they “used to
be” before they metamorphosed.
METAMORPHIC ROCKS (#12-16)
NAME
SLATE
DESCRIPTION
Dark bluish-gray, in fine layers,
dense, no air pockets. Formed by
metamorphosed shale.
Set a piece of shale
here 
SCHIST
(shist)
for comparison!
Dark and light, sparkly, slightly in
layers. Formed by
metamorphosed slate (which was
shale before that).
Compare with slate, which is one
space higher up in this table.
MARBLE
Usually white or light and
”sugary,” sometimes with stripes.
Formed by metamorphosed
limestone.
Set a piece of limestone
here 
QUARTZITE
(KWORTS-ite)
for comparison!
Usually reddish, pinkish or
purplish. Formed by
metamorphosed sandstone.
Set a piece of sandstone
here 
GNEISS
(nice)
for comparison!
Black and white (or black and
pink) bands or layers, small
crystals, dense, no air pockets.
Often formed by metamorphosed
granite.
Set a piece of granite
here 
for comparison!
PUT IT HERE!
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