Chapter 3 Sec 3 Metamorphic Rocks

Let’s Review: What is an igneous rock? What does the Latin word for Igneous mean? How does it form? What two ways is it classified? How does it change into different rocks?

Chapter 3 – Section 3 Metamorphic Rocks What is a metamorphic rock? The word metamorphic means to “change form”

Notes Chapter 3 – Section 3 Metamorphic means to “change form”

Metamorphic rocks are rocks that have changed because of temperature and pressure or the presence of hot watery fluids.

Metamorphic rocks - change because of temperature and pressure or the presence of hot watery fluids.

The form and/or the composition of the rock can change. See pg. 67 – figure 7. When heat and pressure are applied to granite (an igneous rock), the new rock is gneiss.

Example – when heat and pressure are applied to granite (igneous rock) a new rock called gneiss is formed. Igneous granite.......................... changes to metamorphic gneiss

Metamorphic rocks can form from sedimentary rocks, igneous rocks, or other metamorphic rocks This is the rock cycle

As pressure and temperature continue to increase over time, one type of rock can change into several different metamorphic rocks

Here’s a short clip about metamorphic rock

Heat and Pressure Where does the heat and pressure come from? Rocks below Earth’s surface are under tremendous pressure from rock layers above them. Temperature increases with depth in the Earth.

Sometimes temperature and pressure are great enough to melt rock, forming magma

Sometimes, the rock is not actually melted but the pressure can flatten the mineral grains in rocks, therefore making a new rock.

As pressure and temperature continue to increase over time, one type of rock can change into several different metamorphic rocks.

Example – With heat and pressure Shale can turn into slate. With additional heat and pressure, slate can turn into phyllite. Adding more heat and pressure, phyllite turns into schist…and so on.

Example Shale (parent rock) Slate Phyllite Schist Adding heat and pressure to each type of rock causes it to change and a new type of rock forms Slate Phyllite Schist

Hot Fluids Fluids can also move through rock Fluids are mostly water and dissolved elements or compounds – they can react and chemically change the rock into something else.

(See pg. 68 – figure 8) Rocks surrounding a hot magma body can react to the hot magma. These fluids are mainly comprised of water and carbon dioxide.

Classifying Metamorphic Rocks Foliated or nonfoliated?

Foliated metamorphic rocks – when mineral grains line up in parallel layers. Example: slate and gneiss Slate is layered and often used for paving around pools and patios because the layers are pressed so firmly together that they are watertight

Folitated

Slate comes in several colors. Used for chalkboards, more expensive upper end pooltables, yard stepping stones….

Classifying Metamorphic Rocks Foliated – when mineral grains line up in parallel layers. Example: Slate, gneiss

Nonfoliated metamorphic rocks – minerals do not form layers. Examples: quartzite and marble

marble

Nonfoliated – minerals do not line up in layers Example: quartzite, marble (both have several different colors)

Here’s a short clip about diamond which is a mineral formed from metamorphic rock