RocksGroup5

Rocks
A rock is a naturally occuring solid consisting of minerals that are mixed together.

Are formed when molten magma cools and divided into either plutonic or volcanic rocks. Plutonic rocks are rocks that cool slowly and crystallizes slowly inside the Earth's crust. An example is granite. Volcanic rocks is when magma reaches the Earth's surface. Examples include basalt and pumice.
 * Igneous Rocks**

Are formed by deposition of clastic sediments, organic matter or evaporites. This is followed by the compaction and cementation of the rock. Sedimentary rocks form on or near the Earth's surface. The word clasticcome from the word klastos, which means broken. Coarse-grained rocks are sedimentary rocks consisting of mineral fragments.
 * Sedimentary Rocks**

Color Streak is the color of the powdered mineral Luster is the reflection or refraction Flouroscene is ultraviolet light Hardness of a rock is based on Moh's scale of hardenss Cleavage is the tendency of the mineral to split along planes Magnetism is when a rock is attracted to a magnet.
 * Properties**

The rock cycle is the transformations among the three main rock types: sedimentary, metamorphic and igneous rocks.


 * Igneous Rock**


 * Basalt**


 * Pumice**


 * Sedimentary Rock**


 * Moh's Scale Of Hardness**


 * The Rock Cycle**

Metamorphic Rocks
Metamorphic rocks form from existing rock by heat, pressure and chemicals

__Metamorphism__ - process of forming metamorphic rocks inside the lithosphere. This makes the rocks more dense and less porous.

__Recrystallization__ - process of increasing the size of mineral crystals. This can also change the mineral composition without melting.


 * Texture is one way to identify a metamorphic rock**


 * The rocks are classified into two groups**

__Foliation__ - parrarel layer of minerals caused by pressures on the rock. It has bands and layers created on the rock. Examples include slate and gneiss. High pressure was exposed during metamorphism causing the mineral to form with the axes perpendicular to the rock.

__Non-foliation__ - does not display banding and layering that foliation has. Examples include marble and quartzite.


 * There are several types of metamorphism**

__Regional metamorphism__ - when large areas of rock are under intense heat and pressure causing them to change form, resulting in foliation. One cause of this is an increase of temperature and pressure with depth. Another cause is tectonic plates along with convergent plate boundaries and continental collison.

__Contact metamorphism__ - occurs when hot magma goes into overlaying rock and bakes the rocks in contact with it

__Dynamic metamorphism__ - crushing and ductile flow of rocks


 * Mylonites are rocks that are formed along fault lines**


 * Changes in the rock are less drastic, meaning no foliation and less rock is affected**


 * Different combinations of temperatures and pressures result in grades of metamorphism**

Low grade includes low temperatures and low pressures including a particle suit of minerals and textures. Metamorphism takes place at temperatures between 200 and 320 degrees Celcius and has low pressure. They are characterized by an abundance of hydrous minerals.

High grade includes high temperatures and high pressures and a different suit of minerals and textures. Metamorphism takes place at temperatures higher than 320 degrees Celcius and has high pressure. As the grade increases, hydrous minerals become less hydrous by losing water. Also, non-hydrous minerals become common.


 * Pressures and temperatures increase with depth. When temperature and pressure become high enough, rocks melt and form magma. When high temperatures and pressures combine, it changes the texture, mineral compostion and chemical composition of a rock without melting it. This forms the metamorphic rocks.**


 * There are many types of metamorphic rocks**

__Serpentine__ - heavy metamorphic rock that forms by hydration

__Blue schist__ - high pressure combined with low temperatures create blue minerals

__Soapstone__ - largely composed of the mineral talc and is rich in magnesium

__Ecoglite__ - formed by regional metamorphism of basalt under high pressures and temperatures


 * Burial pressure is when pressure increases with depth due to weight of the overlaying rocks**


 * In some settings, new materials are introduced by hydrothermal solutions. The process is hot water with dissolved ions. Metallic ore deposits are formed this way.**


 * Sedimetary and igneous rocks can transform into metamorphic rocks**


 * Slate, a type of metamorphic rock**


 * Metamorphism Chart**


 * Mylonites**


 * Serpentine Rock**


 * Gneiss**
 * Marble**
 * Quartzite

Links [|www.en.wikipedia.org]** [|www.earthscienceteamperiod7.wikispaces.com]