RocksGroup2

Magma and Lava play a large role in the forming of rocks. rocks formed in magma usually tend 2 have crystals, large or small. This is because of the time the rock spends in the heat, and the time it has to form these crystals. On the other hand, rocks formed in lava tend not to have any crystals at all. Like the opposite of the magma rocks, these rocks cooled and solidified to quickly.
 * //__Igneous Rock__//**
 * An intrusive or extrusive igneous rock formed from the cooling and crystallization of magma or lava.

Igneous rocks are formed through slow or fast solidification or minerals. Depending on where it cools depends on the way the rock looks. Rocks cooling on the outside of Earth's surface are called EXTRUSIVE ROCKS. For example, obsidian, is a glassy, extrusive igneous rock that shoots up from a volcano and cools almost instantaneously. This rock has no crystals because the crystals had no time to form. You can see from its smooth, non crystalline texture that this rock cooled quickly. Other rocks may cool quickly, not be as smooth and glassy, but have little or no crystals. These rocks are called Fine-grained rocks. Igneous rocks with crystals that formed inside Earth's crust are called INTRUSIVE ROCKS. The Igneous Rocks with crystals are labeled either coarse grained or very coarse grained. The only difference in these two kinds of rocks are the amounts of crystals. Gabbro is a coarse-grained rock with visible crystals and and the texture to match it. Pegmatite is a very coarse-grained rock with an exuberant amount of visible crystals.

Texture and color are another important factor in determining an igneous rock. A rock can either be regular, meaning with a smooth texture or with a rocky texture due to the amount of crystals. Or the rock can have holes in it due to gas pockets exploding when the extrusive rocks reach the Earth's surface. Pumice (the rock above) is an extrusive vesicular rock because as you can see it has the gas pockets.

Colors for igneous rock can either be on the Felsic side of the I gneous Rock Identification Chart or on the Mafic side. Felsic simply means that the rock has high silica (a mineral making up some of the igneous rocks) content and quartz, giving the rocks their lighter colors. Mafic means that the rock has lower silica content, no quartz, and a lot of pyroxene, giving the rocks their darker colored appearance. **  //__**Sedimentary Rocks**__// Sedimentary rocks form through the process of sedimentation. **Sedimentation** is the process causing minerals to be broken down by weathering and deposition. **Weathering** is the process of a rock being broken down by water and wind, while **deposition** is when a rock is carried and travels due to water and or wind.

The little pieces of rock that are broken down by sedimentation are called **sediments.** Conglomerate is a mixture of any rock (sedimentary, igneous, or metamorphic) that was cemented together. Shale was also formed from compaction, but in a different way. Shale forms in layers, showing that extreme weight and pressure where applied on top of it. As time passes, the clay shale was formed from piles and piles on top until there are enough layers to completely flatten the clay into hard rock.
 * ANY ROCK CAN BE TURNED INTO SEDIMENTS THROUGH SEDIMENTATION
 * After a rock is turned into sediments, compaction or cementation ** can turn the sediments into a sedimentary rock.

-texture -acid reactivity -layers -flat or curved -cementation or compression (compaction) -if there are pores -if it has fossils
 * Sedimentary Rocks are classified are by:

**Three Types of Sedimentary Rocks: -**Clastic**-have granular materials, consist of quartz and clays, have visible particles of little sediments,** can split easily, can be very fine to coarse grained. -Organic (Bioclastic)- having crstals that can vary from microscopic to very coarse, made from living things - Chemical (Crystalline)- formed in deep, dry, underwater sea caves with concentrated centers of salty sea water **