Ultimate Guide to Rocks

From their natural beauty to their practical uses, rocks are a very important part of our world. The lithosphere, Earth's outer solid layer, is made of rocks. Rocks help preserve the past and allow us to better understand the way life was before us. Rocks also are the gateway to the future, that as a natural resource, we can use to further our quality of life. The subject of rocks is very beneficial to all. Historians, archeologists, geologists and environmental scientists, have several perspectives about rocks which are all interwoven to create better opportunities for man.

Formation process

Rocks are formed in various ways. This explains why rocks are unique in their qualities. For example, some rocks are formed when molten magma solidifies on the earth's surface. Molten magma forms as a result of a volcanic eruption. Other rocks are formed as a result of minerals and particles settling on the Earth's surface. Sometimes, harsh weather conditions act on an already existing rock to form another rock that looks completely different from their parent materials.

• How Rocks Are Formed: Explains how the three main rock groups are formed.

• How rocks are named: Geologists have a way of classifying rocks. They look into the mode of formation and characteristics of rocks formed.

• Agents of metamorphism: Factors that form a change on existing rocks are high temperatures and chemicals from rainwater.

• Igneous, Metamorphic, and Sedimentary Rock Formations: Animations that show how each rock formation is made.

• Rock Cycle: A collection of visualizations on the rock cycle.

Types of rocks

There are three different types of rocks. They are the igneous, sedimentary and metamorphic. This classification is solely owed to their modes of formation. Igneous rocks are formed from melted rocks or silicates that cool or solidify. This melted rocks or silicates are normally called magma. The other type of rock is the sedimentary rock and they can be formed on land or in water. Metamorphic rocks are formed as a result of a transformation of either an igneous or sedimentary rock.

IGNEOUS

• Igneous Rocks: Has a variety of information on igneous rocks.

• Minerals in igneous rocks: Some minerals in igneous rocks are biotite, potassium feldspar and amphibole.

• Intrusive and extrusive igneous rocks: Intrusive rocks are formed by magma that solidifies inside the earth while extrusive igneous rocks are formed by magma that solidifies outside the earth.

  SEDIMENTARY

• Examples of common sedimentary rocks: Some types of sedimentary rocks are limestone, chalk and sandstone.

• Sedimentary Rocks: This page has a variety of information on sedimentary rocks.

• Minerals found in sedimentary rocks: The two types of minerals found in sedimentary rocks are allogenic minerals and authigenic minerals.

  METAMORPHIC

• What kinds of metamorphic rocks form? Certain conditions are important for a particular kind of metamorphic rock to be formed.

• Minerals and polymorphs of metamorphic rocks: An exclusive mineral in metamorphic rock is kyanite. Graphite and diamond are metamorphic polymorphs.

• Examples of metamorphic rocks: Some examples of metamorphic rocks are schist and slate.

Rock classification

Since the three rock types have different properties, it is important to be able to determine which rock is which. An effective way of distinguishing is by knowing the characteristics of the different rocks. Based on their formation, rocks have different characteristics from one another. For instance, sedimentary rocks look different from metamorphic rocks because of extremely high temperature and pressure during their formation. Some of the basic characteristics are:

• Foliated texture: Metamorphic rocks are hard in nature. They also form crystals.

• Absence of fossils: Igneous rocks generally do not form fossils because their parent rocks have been subjected to great heat and pressure.

• Possess different colors: Due to high and varying effects of temperature on the sides of the parent material, the resulting metamorphic rock may have alternate forms of white and black bands.

• Classification of Common Rocks: Explains certain features to help one classify rocks.

• Texture of igneous rocks: Igneous rocks have different sizes of crystals because of the way they cool on formation.

Rocks impact on society

Rocks have had a tremendous impact on the advancement of the human race. Rocks have been used by humans for more than 2 million years. Tools and weapons were commonly made from rocks. To this day, rocks continue to be used in the construction of buildings as well as an energy source.

• Used in building: Houses and bridges are used in building rocks. Rocks form a major part of the cement.

• Used in the printing press: About 27,000 pounds of clays are used to improve the quality of the pages of newspapers and magazines.

• Power generation.: Coal; a sedimentary rock can be used to generate power.