Geology Chapter 2 Rocks and Minerals

Atom

the smallest particle into which an element can be divided while still retaining the chemical characteristics of that element.

Nucleus

is at the center of an atom, contains one or more particles with a positive electrical charge (protons) and usually some particles of similar mass that have no charge (neutrons).

Electrons

negatively charged and circles the nucleus.

Atomic Mass Number

the sum of the number of protons and the number of neutrons in a nucleus.

Ion

when the atom has a positive (cations) or negative (anions) electrical charge.

Compound

a chemical combination of two or more chemical elements. bonded together in particular proportions, that had a distinct set of physical proportions.

Ionic Bonding

bond is based on the electrical attraction between oppositely charged ions.

Covalent Bonding

bonds between atoms that form if the atoms share electrons.

Mineral

a natural occurring, inorganic, solid element or compound with a definite chemical composition and a regular internal crystal structure.

Organic

a carbon based life form.

Cleavage

a distinctive way some minerals may break up when struck.

Streak

the color of the powdered mineral as revealed when the mineral is scraped across a piece of unglazed tile.

Hardness

the ability to resist scratching.

Color

the actual color of the mineral.

Luster

the appearance of the surfaces -- glassy, metallic, pearly, etc.

Density

mineral weight over weight of equal water volume.

Silicates

largest compositional group of minerals and contains two of the most common elements in earth's crust: oxygen and silicon.

Ferromagnesian

the general term used to describe silicates with iron and magnesium, that are usually a darker color.

Non-Silicates

do not have silicon and oxygen in their chemical formulas, but like silicates, each mineral non-silicates group is defined by some chemical constituent or characteristic that all members of the group have in common.

Carbonates

all contain carbon and oxygen combined in the proportions of one atom of carbon to three atoms of oxygen.

Sulfates

all contain sulfur and oxygen in the ratio of 1:4.

Sulfides

the mineral that occurs when sulfur is present without oxygen.

Oxides

minerals containing just one or more metals combined with oxygen, and lacking the other elements necessary to classify them as silicates, sulfates, carbonates, and so forth.

Native Elements

minerals that consist of a single chemical element, and the minerals' names are usually the same as the corresponding element. Can NOT be bonded.

Bowen's Reaction Series

at a certain temperature, minerals become stable.

Crystalline Structure

atoms in a mineral are specifically ordered.

Crystals

rare minerals displaying flat external faces and form best in open cavities.

5 recognized types of bonds

1. covalent
2. ionic
3. metallic
4. Van der Walls
5. hydrogen

Fracture

how a mineral breaks without cleavage because there is no plane of weakness.

Rock

a solid cohesive aggregate of one or more minerals, or mineral materials.

Igneous Rock

a rock crystallized from molten material, formed at high temperatures.
Keys: interlocking crystals
Identify by: composition and texture
Examples: granite, gabbro, bassalt, rhyolite

Sedimentary Rock

a rock formed from sediment, debris of preexisting rocks deposited at low temperatures at the earth's surface.
Keys: composed of clasts of other rocks
Identify by: grain size, shape and composition
Example: sandstone, conglomerate, shale and limestone

Rock Cycle

rocks are continually being changed by geological processes.

Metamorphic Rock

a rock formed from the deformation of pre-existing rocks due to heat and pressure.
Keys: foliation (apparent stacking or banding)
Identify by: severity of deformation and composition
Example: gneiss, schist, slate, phyllite and marble