Chapter 3 and 4 Test

Mineral

Are naturally occurring Are a solid Are inorganic (not from living matter) Have a definite chemical composition Have an orderly arrangement of atoms or ions

CHEMICAL SEDIMENTARY ROCKS

As water flows through cracks or empty spaces between rock, it can dissolve minerals in the rock. Eventually rivers carry the dissolved material to the ocean where they contribute to the saltiness of the ocean. Water can become saturated with dissolved minerals, causing particles to crystallize out of the water and form new minerals. Chemical rocks form when minerals crystallize directly from water. Rock salt, rock gypsum, and limestone are examples of chemical sedimentary rocks. Chemical sedimentary rocks often have an interlocking crystalline texture.

CONTACT AND REGIONAL METAMORPHISM

Contact metamorphism occurs when magma comes in contact with existing rock, and its thermal energy and gases interact with the surrounding rock, forming new metamorphic rock. Contact metamorphism can increase crystal size or form new minerals and change rock. Regional metamorphism is the formation of metamorphic rock bodies that are hundreds of square kilometers in size. This process can create an entire mountain range of metamorphic rock. They Himalayas in Asia and the Appalachian Mountains in the eastern United States exhibit structures associated with regional metamorphism.

Sedimentary rocks

Forces such as wind, running water, ice and even gravity cause rocks on Earth's surface to break down. Sediment is rock material that forms where rocks are broken down into smaller pieces or dissolved in water as rocks erode. These materials, which include rock fragments, mineral crystals, or the remains of certain plants and animals, are the building blocks of sedimentary rocks. Sedimentary rocks form where sediment is deposited. Such environments include: mountain valleys, river banks, on the beach or even your backyard.

METAMORPHIC ROCK IDENTIFICATION

Geologists study the texture and composition of minerals to identify metamorphic rocks. Metamorphic rocks are divided into two categories based on texture: Foliated Rocks Nonfoliated Rocks

Rare Metals

Gold occurs in a ratio of 1 part gold per 1 billion parts rock in Earth's crust, but form in concentrations large enough to be mined for profit. Not only is it desired for jewelry, but conducts electricity and does not corrode. Technology industry is dependent on many other metallic minerals. Platinum is used in catalytic converters to help regulate gas emissions from automobiles. Scientists are researching the use of platinum for fuel cells in electric cars.

Intrusive Rocks

Igneous rocks that form as magma cools underground are called intrusive rocks. Because magma is insulated by solid rock, the magma cools more slowly than the lava on Earth's surface. When magma cools slowly, large well-defined crystals are formed. The arrangement of crystals in intrusive rock is random, interlocking like jigsaw puzzle pieces.

Grains

Individual mineral crystals, broken bits of minerals, or rock fragments make up these grains

Igneous Rock Formation

Magma is molten rock below Earth's surface and lava is molten rock that has erupted onto Earth's surface. When magma and lava cool and crystalize, igneous rocks form. Lava cools quickly as it comes in contact with cooler air, but magma cools and crystallizes slowly beneath Earth's surface.

MINERALS THAT FORM FROM MAGMA

Magma is molten rock found beneath Earth's surface. When molten rock erupts on or near Earth's surface it is called lava. As lava (and ash) cool above and/or below Earth's surface, atoms and ions arrange themselves and become mineral crystals. Crystals differ in size based on the cooling rate: Small crystals form when lava cools quickly on or near Earth's surface Large crystals form as magma cools slowly (and crystallizes) below Earth's surface

Non-silicate

Member of the mineral group that does NOT have silicon in its crystal structure

Silicate

Member of the mineral group that has silicon and oxygen in its crystal structure Feldspar is the most common silicate mineral in Earth's crust

Nonfoliated Rocks

Metamorphic rocks that have mineral grains with a random, interlocking texture are nonfoliated rocks. There is no obvious alignment of the mineral crystals in nonfoliated metamorphic rock. Instead, the individual crystals are blocky and approximately equal in size.

SEDIMENTARY ROCK FORMATION

Mineral and rock fragments can be transported by water, glacial activity, gravity or wind. The sediments are eventually deposited, or laid down, where they can accumulate into layers. The layers thicken over time, younger sediment burying older sediment. The weight from the layers of sediment forces out fluids and decreases the space between grains during a process called compaction. Compaction can lead to a process called cementation. When minerals dissolved in water crystallize between sediment grains, the process is called cementation. Mineral cement holds the grains together. In summary, sedimentary rocks form when sediment, rock fragments, minerals or organic materials are deposited, compacted and cemented together. Sedimentary rocks also form during evaporation when minerals crystallize from water or when organisms remove minerals from the water to make their shells or skeletons.

Examples of Silicate

Quartz, Potassium Feldspar and Plagioclase Feldspar

NONMETALLIC METALS

Raw materials used for road construction, ceramic products, building stone, and fertilizers are all examples of nonmetallic mineral resources. Sand is just one example of a nonmetallic mineral resource.

METAMORPHIC ROCK FORMATION

Rocks are affected by changes in temperature and pressure. These rocks are called metamorphic rocks. Metamorphism is any process that affects the structure or composition of a rock in a solid state as a result of changes in temperature, pressure, or the addition of chemical fluids. Most metamorphic rocks form deep within Earth's crust, where they form under high temperatures and high pressure. But unlike igneous rock, metamorphic rock does not crystallize from magma and unlike sedimentary rock, metamorphic rock do not result from erosion and deposition.

The Rock Cycle

Rocks are changing all the time. You usually don't see it because it happens so slowly. The series of processes that change one type of rock into another type of rock is called the rock cycle. Forces on Earth and deep within Earth's surface drive this cycle. This cycle describes how one rock type can change into another rock type through natural processes.

CLASTIC SEDIMENTARY ROCKS

Sedimentary rocks that are made up of broken pieces of minerals and rock fragments are known as clastic rocks. The broken pieces and fragments are called clasts. Geologists classify clastic rocks according to clast size and shape.

Sedimentary Rock Identification

Similar to igneous rocks, sedimentary rocks are classified by how they are formed. Three such categories for sedimentary rocks are: Clastic Sedimentary Rocks Chemical Sedimentary Rocks Biochemical Sedimentary Rocks

Foliated Rocks

The metamorphic rock, gneiss, is an example of a foliated rock. Foliated rocks contain parallel layers of flat and elongated materials. Foliation is a common feature in metamorphic rocks.

Igneous Rock Identification

Two characteristics to help identify all rocks are texture and composition. Geologists identify igneous rock using the arrangement and size of mineral crystals in the rock. Mineral composition can also be used for igneous rock identification. Texture: By studying the rock's texture, Geologists determine whether a rock is intrusive or extrusive. If the crystals are small or impossible to see without a magnifying glass, the rock is extrusive. If the crystals are large enough to see and have an interlocking texture, they rock is intrusive. Composition: Geologists study the mineral composition of igneous rocks and are classified, in part, based on their silica content. Light colored minerals contain greater amounts of silica, dark colored minerals contain less. Greater amounts of silica are found in intrusive rock, less silica is found in extrusive rock.

MINERALS THAT FORM FROM HOT SOLUTIONS

Water from Earth's surface can flow through cracks in Earth's crust into deep and hot environments. Sometimes, these hot solutions carry large amounts of dissolved solids. Eventually the dissolved solids form minerals. For example: gold can form, when conditions are just right, when crystallizing in hot solutions filling cracks in a rock.

MINERALS THAT FORM FROM COOL SOLUTIONS

Water that flows from rain or melting snow moves along Earth's surface, interacting with minerals in rock and soil. The water dissolves the minerals along with other elements. As water evaporates, solids in the water crystallize forming minerals. For example: the mineral halite (rock salt) formed when water from a shallow lake evaporated. Sometimes minerals can crystallize from water in environments that are not dry. For example: saltwater can become saturated with dissolved salts (in other words, it can't hold anymore salt), so excess salt makes the ocean salty.

Igneous rocks

When magma (molten or liquid rock underground) or lava (molten or liquid rock that erupts on Earth's surface) cool, they crystallize and create igneous rocks. Igneous rocks form in a variety of environments including subduction zones, mid-ocean ridges, and hot spots where volcanoes are common.

Metamorphic rocks

When rocks are exposed to extreme heat and pressure, they can change to metamorphic rocks. Chemical fluids can also cause rocks to become metamorphic. The minerals that make up the rock change as well as the texture, or arrangement of grains. Metamorphic rocks can form from any igneous or sedimentary rock or even another metamorphic rock.

TEMPERATURE AND PRESSURE

When rocks experience an increase in temperature and pressure, they behave like bendable plastic. Without melting, the rocks bend and fold. This permanent change in shape by bending and folding is called plastic deformation. It's one way the texture of a rock changes during metamorphism. Plastic deformation occurs during uplift events when tectonic plates collide and form mountains, such as the Himalayas in Asia. The rock that changes during metamorphism is called the parent rock.

Extrusive Rocks

When volcanic material erupts and cools and crystallizes on Earth's surface, it forms a type of igneous rock called extrusive rock. Materials such as lava and ash, solidify and form extrusive igneous rock. Lava can cool quickly on Earth's surface, which means there might not be enough time for crystals to grow. Therefore, extrusive rocks have fine-grained texture.Obsidian is an example of volcanic glass. Magma stored underground can contain dissolved gases. As magma moves towards Earth's surface, pressure decreases and the gases begin to separate from the molten mixture. When gas-rich lava erupts from a volcano, gases escape leaving holes in the rocks that form. Pumice is an example of rock with holes left by gases.

Rock

a natural, solid mixture of minerals or grains. Geologists call the fragments that make up a rock grains

Gemstone

a rare and attractive mineral that can be worn as jewelry. The bright luster and high ranking hardness are part of what make these stones so valuable.

BIOCHEMICAL SEDIMENTARY ROCKS

a sedimentary rock that was formed by organisms or contain the remains of organisms. The most common biochemical rock is limestone. Coal is another example of biochemical rock, composed of the remains of plants and animals from prehistoric swamps. Over time, organic remains were buried and compacted eventually changing into sedimentary rock.

Color

color alone is not able to identify minerals because many different minerals are the same color; variations of colors can help identify different chemical impurities

Density

degree of compactness of substance or object; mass divided by volume

Texture

grain size and the way grains fit together in a rock; when classifying, geologists look at grain and mineral size within the rock, the arrangement of the grains and the overall feel of the rock; texture can also help determine the environment in which the rock formed

Three major rock types

igneous, sedimentary, metamorphic

Crystallization

particles dissolved in a liquid or a melt solidify and form crystals; minerals can crystallize from: Cool Solutions Hot Solutions Magma

Mineralogist

scientists who study the distribution of minerals, mineral properties, and their uses; they identify minerals based on: Color Luster Streak Hardness Cleavage and Fracture Density Other Special Properties

Other Special Properties

some minerals can be identified by their unique, distinct properties. For example, they may have a unique texture (graphite is greasy, talc is smooth) or they may react when in contact with hydrochloric acid (Calcite fizzes) or a mineral might have a distinct odor (Sulfur smells like a match) or it may glow when in contact with ultraviolet lighting (called fluorescence; calcite and fluorite both fluoresce) or a mineral might be magnetic (Magnetite is magnetic).

Streak

the color of a mineral in powdered form; only useful for identifying minerals that are softer than porcelain; nonmetallic minerals generally produce a white streak

Composition

the minerals or grains present in a rock can help determine where the rock formed

Hardness

the resistance of a mineral to being scratched; German mineralogist developed a scale to compare hardness called the Mohs Hardness Scale; 1 is assigned to the softest (talc) and 10 to the hardest (diamond)

Luster

the way a mineral reflects or absorbs light at its surface; minerals that are also metal (copper, silver, gold) reflect light and have the shiniest luster (called metallic luster); nonmetallic minerals have luster types that might be shiny, but are not reflective like metal; minerals that lack shiny luster are often called earthy or dull; luster depends on the mineral's chemical composition

Fracture

when a mineral breaks and forms uneven surfaces

Cleavage

when a mineral breaks with smooth, flat surfaces