Chapter 3 Rocks and Minerals
Student Notes: Lesson 4 Metamorphic Rock
Main Idea:
Extreme heat and pressure can cause any kind of rock to change to a metamorphic rock. The rock
cycle shows how rocks are constantly changing.
Vocabulary
Pressure (172) – a force pushing on an object
Metamorphic rock (172) – rocks formed by extreme heat and pressure deep inside Earth
Geologist (178) - scientists who study rocks
Rock cycle (180) – cycle by which rocks change from one form to another
How are metamorphic rocks formed?
Main Idea:
Metamorphic rocks form deep inside Earth from great heat and pressure.
Supporting Details:
1. Layers of rock on top of layers of rock causes pressure on the rocks which squeezes them
together.
2. Temperatures under Earth’s surface can be extreme.
3. Metamorphic rock forms as a result of the extreme heat and pressure.
a. The physical properties change from what the rocks originally were
b. Mineral make-up of the rocks can change as they become metamorphic
4. Metamorphic rock can be formed from sedimentary, igneous, and even other metamorphic
rocks.
5. Before and after
a. Granite (igneous) turns into gneiss
b. Limestone (sedimentary) turns into marble
c. Sandstone (Sedimentary) turns into quartzite
d. Slate (metamorphic) turns into schist
What are the properties of some metamorphic rocks?
Main Idea:
Metamorphic rocks are identified by their properties and minerals.
Supporting Details:
1. Metamorphic rock has different properties because each is made from a different material.
The amount of heat and pressure determines its properties.
2. Gneiss
a. Has thin layers (bands) that can be straight or wavy
b. Has large and easily seen crystals
c. Coarse rough texture
3. Quartzite
a. No layers
b. Looks like sandstone from a distance
c. Similar color and is made from small mineral crystals
d. Has a medium texture
4. Marble
a. No layers
b. Crystals vary in sizes
i. Small crystal size – fine texture
ii. Large crystal size – coarse texture
5. Slate
a. Settles into layers
b. Small crystals that are packed together and not easily seen
c. Small crystals give slate a fine, smooth texture
What are some uses of metamorphic rock?
Main Idea:
Metamorphic rock is used in buildings, sidewalks, statues, jewelry and many other items.
Supporting Details:
1. Slate is used to make tiles for walkways. Slate is also used for roofs because it is waterproof.
2. Marble, which forms from limestone, is used for buildings and statues. Marble does not break
apart in layers when you carve it.
3. Lapis lazuli is formed from limestone and is used to make jewelry.
4. Quartzite is used in glassmaking and ceramics.
5. Some metamorphic rock is ground up into small chunks to make gravel.
6. Anthracite is a form of coal that is harder than its sedimentary form and burns cleaner.
How can you be a rock detective?
Main Idea:
The different types of rocks have certain properties that help geologists identify them.
Supporting Details:
1. Geologists use a rock’s physical properties to classify it. Texture, crystal shape, size, and layers
can help you become a rock detective.
2. Clues to identify sedimentary rock
a. Rocks that contain fossils of once- living things
b. If it can be easily broken
3. Clues to identify igneous rock
a. Smooth, glassy texture
b. Shiny and twinkle when held to the light
c. Hard and show no layering
4. Clues to identify metamorphic rock
a. Color bands
b. Presences of certain minerals (talc, graphite)
What is the rock cycle?
Main Idea:
The rock cycle is a never-ending cycle by which rocks change from one type to another.
Supporting Details:
1. Igneous rock
a. Igneous rock can be broken into bits and get carried away through weathering and
erosion. As it settles down and presses / cements down on other rock, it becomes
sedimentary rock.
b. Extreme heat and pressure applied to igneous rock can change it into metamorphic
rock.
2. Sedimentary rock
a. Heat and pressure cause sedimentary rock to change into metamorphic rock
b. Extreme heat can cause sedimentary rock to melt and come out as lava. When it cools
and hardens, it becomes igneous rock.
3. Metamorphic rock
a. Extreme heat can cause metamorphic rock to melt. As it cools and hardens, the
metamorphic rock becomes igneous rock.
b. Metamorphic rock can be broken into bits and get carried away through weathering
and erosion. As it settles down and presses / cements down on other rock, it becomes
sedimentary rock.