Earth & Life Science: Minerals and Rock Cycle

Lesson 2 : Rocks-Forming Minerals and The Rock Cycle

minerals

the building blocks of rocks

rock-forming minerals

these minerals are common and abundant on earth’s crust

mineralogy

branch of geology that deals with the study of minerals

5 characteristics of a mineral

naturally-occurring

inorganic

solid

crystalline structure

can be represented by a chemical formula

naturally-occurring

a mineral that has been formed by geologic processes without any human intervention

inorganic

a mineral that is formed by inorganic processes and does not contain any organic compounds

solid

a mineral should exhibit stability at room temperature, which can only be attained if it is solid

crystalline structure

minerals look like crystals since the arrangement of their atoms is ordered and repetitive

can be represented by a chemical formula

most minerals are chemical compounds and can be represented using a fixed or variable formula

11 physical properties of a mineral

color

streak

luster

odor

tenacity

hardness

cleavage and fracture

transparency

specific gravity

crystalline structure

magnetism

color

a property of a mineral that is easiest to identify and also considered an unreliable property to use when identifying the mineral

streak

a property of a mineral that is in powdered form and is often used in identifying the mineral since it is consistent

luster

a property of a mineral that the quality of light that is being reflected by the surface of a mineral and can be classified as metallic, submetallic, or nonmetallic

metallic luster

minerals that look like metals and are shiny

submetallic luster

minerals that develop a dull coating and are not as shiny

nonmetallic luster

minerals that are described as glassy, earthy, pearly, or greasy

odor

a physical property that is the distinct smell of a mineral that is usually released from a chemical reaction when subjected to water, heat, air, or friction

tenacity

a property that refers to the mineral’s resistance to breaking or deforming and can either be brittle, malleable, sectile, or elastic

hardness

a property that measures a mineral’s resistance to abrasion or scratching

mohs scale

friedrich mohs; to determine the hardness of a mineral, a comparative hardness scale assigning numerical values

talc

the softest mineral

diamond

the hardest mineral

cleavage and fracture

a property of a mineral that is used to describe how minerals break into pieces

cleavage

when minerals split along flat surfaces and are divided smoothly and evenly

fracture

a mineral is divided roughly and unevenly because it exhibited without a cleavage plane

crystalline structure

a property that shows how minerals are arranged in an organized manner

transparency

a property of a mineral that indicates the extent of light that can pass through the mineral

magnetism

a property that indicates the ability of a mineral to attract or repel other minerals

specific gravity

a property that measures the density of a mineral and determines how heavy the mineral is by its weight to water

rock cycle

a continuous process of rocks moving from one another wherein rocks change into sedimentary, metamorphic, and igneous

3 processes

weathering

mass wasting

erosion

weathering

the process of disintegration and decomposition of rocks and the result of continuous is loose fragments of rocks

regolith

minerals that cover the surface of the earth

physical weathering

a type of weathering; without changing the rock composition

• rockfrost wedging

• precipitate

• fire

• plants and animals

chemical weathering

a type of weathering; change in the rock composition

• water + acids

• carbon dioxide + h₂o

mass wasting

a process that can be classified according to the type of movement and the material involved and these types of movements are falls, slides, slumps, avalanches, and flows

falls

a type of movement in mass wasting that occurs when materials located on a steep slope move downward without contact with the ground

slides

a type of movement in mass wasting that moves the materials as one, following a nearly straight line down the slope

slumps

a type of movement in mass wasting that are like slides but they move along a curved surface

avalanches

a type of movement in mass wasting that is the most rapidly moving, where loose materials move incoherently or in a chaotic fashion

flows

a type of movement in mass wasting when they become saturated with water and move like liquid

erosion

generally not transported by the influence of gravity and the rocks and sediments are transported with the help of wind, water, and ice

abrasion

a type of erosion when scraping of materials occurs as the sediments being transported; sediments that are transported farther have undergone more abrasion making the sediments smoother and more rounded

deposition

a type of erosion that accumulates or a collective sediments

lithification

after the sediments have undergone weathering, mass wasting, and erosion, they then undergo this process known as “stone making”

compaction

a process of lithification wherein sediments must first be bound closely together

cementation

a process of lithification wherein the groundwater has seeped in between the sediments evaporate, leaving behind precipitates such as silica and calcium carbonate to cement the sediments together

recrystallization

a process of lithification that occurs when mineral grains interlock themselves in the existing rocks, where they continue growing; transformation of minerals

sedimentary rocks

classified and identified according to texter, nature & shape of the sediments, and presence of cement

2 types of sedimentary rocks

clastic and chemical

clastic

sedimentary rocks that are formed by accumulation, compaction, and cementation of different solid particles that came from mechanical or chemical weathering

chemical

sedimentary rocks that contain materials that are formed by the chemical precipitation of minerals as a direct result of physical processes

chemical precipitation

a substance wherein a liquid solution becomes a solid and formed a precipitation

metamorphic rocks

subjected to higher pressures and temperatures

metamorphism

they undergo this process when changing rocks are due to high temperatures without melting

minimal

relatively low pressues

substantial

extreme changes to the parent rock and the pressure is relatively high

3 types of metamorphism

contact

burial

regional

contact metamorphism

a type when magma intruded a cooler rock, exposing the rock to higher temperatures but not high pressures

burial metamorphism

a type when rocks undergoing metamorphism experience not only high temperature but also uniform stress

regional metamorphism

most metamorphic rocks are mostly formed with this type; occurs during mountain building when a large mass of rocks is exposed to differential stress and high temperatures

2 classifications of metamorphic rocs

foliated and nonfoliated

foliated metamorphic rocks

a classification of metamorphic rocks that exhibit parallel alignment of minerals

nonfoliated metamorphic rocks

a classification of metamorphic rocks that produced when there is very little deformation and when the parent rock has equidimensional crystals

igneous rocks

if too much pressure and high temperature, melting occurs and molten rocks are called magma; when they have crystallization it becomes with this type of rock cycle

decompression metling

a decrease in pressure is needed for melting to occur

partial or fractional melting

if the melted rock solidifies, the composition of this new rock would be entirely different and it is responsible for the variation of igneous rocks that are formed

3 common types of magma

basaltic, andesitic, and rhyolitic

basaltic magma

the most common magma on earth and is characterized by its low silica content, high temperature, low viscosity, and low gas content

rhyolitic magma

a magma that has high silica content, low temperature, very high viscosity, and high gas content—the opposite of basaltic magma

andesitic magma

the magma with properties that are in between basaltic and rhyolitic

2 types of igneous rock formation

intrusive and extrusive

intrusive or plutonic

formation occurs underneath earth’s surface

extrusive or volcanic

formation of the igneous rock took place on the surface of the earth

color and texture

when classifying an igneous rock

color

depends on the minerals that are present

light coloration

indication of a high concentration of feldspar, which is rich in aluminum; felsic

dark coloration

indication of high concentrations of olivine and pyroxene which are rich in magnesium; mafic

texture

describes the overall appearance of the rocks based on the size and shape of the crystals and their arrangement

aphanitic or fine-grained texture

if the lava cooled down quickly on or near earth’s surface, texter is smooth

aphanitic igneous rock

have individual crystals that are hard to see with unaided eye

phaneritic or coarse-grained texture

when the magma cools slowly beneath earth’s surface, the result is rough

phaneritic igneous rock

have individual crystals are large enough so that the minerals can be identified with the unaided eye

porphyritic texture

if the rock has not fully cooled and has been placed in a different environment, there will be a combination of different crystal sizes

glassy texture

if the molten rock that was ejected crystallizes immediately; obsidian