GEOL unit1 pt4

Eons

The largest divisions of geological time, consisting of four main eons:Hadean, Archean, Proterozoic, and Phanerozoic.

Hadean Eon

The oldest eon, spanning from 4567 to 4000 million years ago (Ma).

Archean Eon

The eon following Hadean, lasting from 4000 to 2500 Ma, known as "Ancient."

Proterozoic Eon

The eon from 2500 to 538.8 Ma, referred to as "Before Life."

Phanerozoic Eon

The youngest eon, from 538.8 Ma to the present, characterized by "visible life."

Eras

Subdivisions of eons; the Phanerozoic eon is divided into Paleozoic, Mesozoic, and Cenozoic eras.

Paleozoic Era

The oldest era of the Phanerozoic, beginning at 538.8 Ma, known for "early or ancient life."

Mesozoic Era

The middle era of the Phanerozoic, starting at 252 Ma, known as "middle life."

Cenozoic Era

The most recent era, beginning at 66 Ma, referred to as "new or recent life."

Periods

Subdivisions of eras; the Cenozoic era is divided into Paleogene, Neogene, and Quaternary periods.

paleogene period

oldest

quaternary period

youngest

time periods are distinguished by..

mass extinctions

Periods are divided into ___.

epochs

Elements

The most fundamental substances that cannot be separated by chemical means, with around 92 naturally occurring elements.

Atom

The smallest unit of an element, composed of protons, neutrons, and electrons.

atoms are comprised of…

Protons (charge of +1), Nucleus, Neutrons (charge of 0), Electrons (charge of –1), Electrons exist as a cloud of negative charges surrounding the nucleus.

Ions

Atoms that have gained or lost electrons, resulting in a net electric charge.

cations, anions

attraction between ___ and ____ is the bonding force that often holds matter together 

Cation

A positively charged ion formed when an atom loses one or more electrons.

Anion

A negatively charged ion formed when an atom gains one or more electrons.

Chemical Bonds

Attractive forces that hold atoms together, including ionic, covalent, and metallic bonds.

Ionic Bond

A bond formed through the transfer of electrons from one atom to another, resulting in attraction between cations and anions.

Covalent Bond

A bond formed when atoms share electrons to fill their outer electron shells.

Metallic Bond

A bond where positive metal ions attract free-flowing electrons, allowing for conductivity.

Van der Waals Bonding (stick together)

Weak attraction between electrically neutral molecules that have asymmetrical charge distribution

Rock

A naturally occurring aggregate of minerals.

Crystalline Structure

The orderly, fixed pattern of atoms in a crystalline material that defines its physical properties.

Solidification

The process of forming minerals from the cooling and solidifying of magma or lava.

Precipitation

The formation of minerals from dissolved ions in a solution as they reach saturation.

solid-state diffusion

• results from the movement of atoms or ions through a solid to arrange into a new crystal structure 

• Garnets, for example, grow by diffusion in solid rock 

• During this process, they replace pre-existing minerals

Biomineralization

The process by which living organisms produce minerals through metabolic processes.

Metamorphism

The formation of new minerals from existing minerals under high temperature and pressure without melting.

chemical weathering

• minerals unstable at Earth’s surface may be altered to other minerals

• Precipitation directly from a gas can occur around volcanic vents or around geysers 

•  volcanic gases or steam enter the atmosphere and cool, so some gas molecules of some elements are able to bind together 

• some of the bright yellow sulfur deposits found in volcanic regions form in this way

Rock-Forming Minerals

Common minerals that make up most of the Earth's crust, typically less than two dozen.

Silicate Structures

Various arrangements of silica tetrahedra in silicate minerals, including independent tetrahedra, single chains, double chains, sheets, and frameworks.

Halides

• minerals that make up the halide group include those in which the halogen elements of fluorine, chlorine, bromine, and iodine are combined with one or more metals

• includes halite, sylvite, fluorite

• halogen elements are the anion

Nonsilicate Minerals: Oxides

• Oxide minerals have oxygen (O2–) as their anion 

• but we exclude those minerals with oxygen complexes such as carbonate (CO3 2–), sulphate (SO4 2–), and silicate (SiO4 4–) from the oxide group 

• several minerals of great economic importance including the chief ores of iron, chromium, manganese, tin, and aluminum 

• Hematite (iron oxide Fe2O3 )

•  Magnetite (Fe3O4 )

•  Corundum (aluminum oxide Al2O3 )

  
  

Sulfates

•  basic unit of the sulfate minerals is the sulfate anion, SO4 2- 

• sulfate anion combines with metal cation to form the sulfate minerals

•  the metal cation has a +2 charge, which balances the –2 charge on the sulfate ion

• many sulfates form by precipitation out of water at or near the Earth’s surface 

• Common sulfate minerals: 

• Barite (BaSO4 )

• Gypsum(CaSO4 .2H2O)

• Anhydrite(CaSO4)

Silicate Structures: Single Chains 

• In a single-chain silicate, the tetrahedra link to form a chain by sharing two oxygen atoms 

• strongly bonded so cleavage cuts parallel to the chains 

• two planes of cleavage at 90 degrees

The most common of the many different types of single-chain silicates are ______

pyroxenes

____ is the most common mineral in the pyroxene group

Augite

Pyroxenes

dominate mineral in salt, important components of dark-colored igneous rocks, black in color, Two distinctive cleavages at nearly 90 degrees.

Silicate Structures: Double Chains

•  In a double-chain silicate, the tetrahedra link by sharing two or three oxygen atoms

• minerals cleave parallel to the double chains

• two planes of cleavage at 60 and 120 degrees

______ are the most common type of double chain silicates

Amphiboles

Silicate Structures: 2D Sheet Silicates

• All the tetrahedra in this group share three oxygen atoms and therefore link to form two-dimensional sheets

• Other ions, and in some cases water molecules, fit between the sheets in some sheet silicates

• Because of their structure, sheet silicates have cleavage in one direction and occur in books of very thin sheets

• bonds between sheets are weak 

• This group includes micas and clays (which occur only in extremely tiny flakes)

Muscovite is a Common member of the ___ family

mica

Muscovite

• Excellent cleavage in one direction 

• Clear, thin sheets 

• Produces the “glimmering” brilliance often seen in beach sand

Feldspars 

• Most common mineral group

• Forms under a wide range of temperatures and pressures 

• Exhibit two directions of perfect cleavage at 90 degrees

Quartz 

• Only common silicate mineral composed entirely of oxygen and silicon 

• Hard (7) and resistant to weathering

• Breaks with conchoidal fracture 

• Often forms hexagonal crystals 

• Colored by impurities (various ions)

four

In a framework silicate, each tetrahedron shares all ____ oxygen atoms with its neighbors, so the tetrahedra are configured in a threedimensional structure 

Nonsilicate Minerals

Minerals that do not contain silicate; includes halides, oxides, and sulfates.