Geology Lab Exam 1

Definition of a mineral (has five parts):

1) naturally occurring, 2) inorganic, 3) solid at room temperature, 4) regular crystal structure, and 5) defined chemical composition.

Protolith

he original, unmetamorphosed rock from which a given metamorphic rock is formed

Metamorphic grade:

the range of metamorphic change a rock undergoes, progressing from low (little metamorphic change) grade to high (significant metamorphic change) grade

Carbonates:

A class of sedimentary rock whose chief mineral constituents (95% or more) are calcite and aragonite (both CaCo3) and dolomite

Crystalline structure

A crystal structure consists of highly ordered and symmetrical chemical bonds that affect the overall shape and properties of the material

Moh's hardness scale:

A qualitative scale of hardness (Moh's scale) is used to describe the relative resistance of a mineral (or gem) to scratching

Ultra-mafic:

An igneous rock with extremely low silica composition, being made of almost all olivine and pyroxene

Compositional layers of the Earth:

Core, mantle, and crust are divisions based on composition. The crust makes up less than 1 percent of Earth by mass, consisting of oceanic crust and continental crust is often more felsic rock. The mantle is hot and represents about 68 percent of Earth's mass. Finally, the core is mostly iron metal.

Four different kinds of plate boundaries:

Divergent boundaries -- where new crust is generated as the plates pull away from each other. Convergent boundaries -- where crust is destroyed as one plate dives under another. Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other.

Different kinds of crust and their relative densities:

Finally, the two types of crust differ in their composition. Continental crust is made largely of granite , while oceanic crust is mostly composed of basalt . Basalt contains a higher proportion of heavier elements like iron and magnesium, making oceanic crust denser than continental crust (3 g/cm3 vs. 2.7 g/cm3.)

Granofelsic

Granulite is a high-grade metamorphic rock in which Fe-Mg-silicates are dominantly hydroxyl-free; the presence of feldspar and the absence of primary muscovite are critical, cordierite may also be present. The mineral composition is to be indicated by prefixing the major constituents.

Glassy:

If a rock looks like a block of (colored) glass, with no visible mineral crystals,

Igneous grainsize and its implications:

Igneous rocks may be simply classified according to their chemical/mineral composition as felsic, intermediate, mafic, and ultramafic, and by texture or grain size: intrusive rocks are course grained (all crystals are visible to the naked eye) while extrusive rocks may be fine-grained (microscopic crystals) or glass (

Phaneritic:

Of or relating to an igneous rock in which the crystals are so coarse that individual minerals can be distinguished with the naked eye.

Feldspar (two kinds - know them both well):

Plagioclase, often called plagioclase feldspar, is mostly a solid solution of albite and anorthite, although it may contain up to 10 wt % orthoclase.

Two Types of Weathering

Physical weathering involves the breakdown of rocks and soils through the mechanical effects of heat, water, ice, or other agents. Chemical weathering involves the chemical reaction of water, atmospheric gases, and biologically produced chemicals with rocks and soils.

Vitreous:

Resembling glass. Most often used in geology to refer to a glassy

Streak

Streak is simply the color of a mineral powder.

Why does the Earth have a magnetic field (how does this relate to bird migration?):

Thanks to a combination of sensing the Earth's magnetic field through vision and an in-built compass that allows them to orient themselves according to magnetic intensity, migratory birds don't have much trouble finding their way.Jan

Viscosity

Viscosity refers to a fluid's resistance to flowing

What causes volcanoes along certain plate boundaries and which boundaries are these

Volcanoes are one kind of feature that forms along convergent plate boundaries, where two tectonic plates collide and one moves beneath the other.

How density affects plate interactions:

Warm areas expand and become less dense (more buoyant) than their surroundings and rise.

Clast:

a fragment of rock or mineral, ranging in size from less than a micron (too small to see) to as big as an apartment block

Clastic rocks (also called Siliciclastic):

a group of sedimentary rocks consisting of fragments of minerals and rocks derived from pre-existing rocks

Mafic

a kind of igneous rock or even magma that is relatively high in magnesium and iron content

Porphyritic:

a rock that has well-formed crystals visible to the naked eye, called phenocrysts, set in a very fine grained or glassy matrix, called the groundmass.

Uneven fracture:

a rough surface or one with random irregularities

Vesicular:

a small cavity in an aphanitic or glassy igneous rock, formed by expansion of a bubble of gas or steam during solidification of the rock.

Rock

a solid collection of minerals.

Sedimentary grain size terms (e.g., silt, sand, pebble):

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Mica minerals (there are two you need to know):

any of a group of hydrous potassium, aluminum silicate minerals

Gneissic banding:

are arranged into layers that appear as bands in cross section.

Evaporites:

are layered crystalline sedimentary rocks that form from brines generated in areas where the amount of water lost by evaporation exceeds the total amount of water from rainfall and influx via rivers and streams.

Lithification:

complex process whereby freshly deposited loose grains of sediment are converted into rock.

Cleavage planes

e tendency of minerals to split along crystallographic planes as a result of structural locations of atoms and ions in the crystal, creating planes of relative weakness

Magma:

extremely hot liquid and semi-liquid rock located under Earth's surface.

Chemical sedimentary Rocks:

form by chemical precipitation that begins when water traveling through rock dissolves some of the minerals.

Igneous Rock

form when hot, molten rock crystallizes and solidifies. The melt originates deep within the Earth near active plate boundaries or hot spots, then rises toward the surface.

Calcite cementation:

formed by interaction between acidic fluid containing CO2 and calcium silicate or carbonate minerals

Sedimentary rock:

formed from pre-existing rocks or pieces of once-living organisms. They form from deposits that accumulate on the Earth's surface. Sedimentary rocks often have distinctive layering or bedding.

Intrusive igneous rock:

forms when magma is trapped deep inside the Earth. Great globs of molten rock rise toward the surface.

Conchoidal fracture:

fracture with smooth, curved surfaces that resemble the interior of a seashell;

Rheologic layers of the Earth:

lithosphere, asthenosphere, mesosphere, outer core, and inner core.

Lava:

magma (molten rock) emerging as a liquid onto Earth's surface

Organic solids (in the context of sedimentary systems):

materials containing carbon as one of many compounds.

Clevage

mineral that breaks smoothly along specific internal planes, making right angles or flat plains

Schistosity

mode of foliation that occurs in certain metamorphic rocks as a consequence of the parallel alignment of platy and lath-shaped mineral constituents.

General depositional environments for different sedimentary rocks:

part of earth surface that has certain chemical, biology, and physics characteristics where sediments are laid on.

Extrusive igneous rock:

produced when magma exits and cools above (or very near) the Earth's surface.

Foliation

repetitive layering in metamorphic rocks.

Metamorphic rock:

rocks that have become changed by intense heat or pressure while forming.

Crystal habit:

the characteristic external shape of an individual crystal or aggregate of crystals.

Igneous texture:

the features that we see in the rock such as the mineral sizes or the presence of glass, fragmented material, or vesicles (holes) in the igneous rock.

Erosion

the geological process in which earthen materials are worn away and transported by natural forces such as wind or water.

Deposition

the laying down of sediment carried by wind, flowing water, the sea or ice

Rock matrix:

the material in which something is embedded, either the natural rock that holds crystals, fossils, pebbles, mineral veins, and the like, or the fine-grained materials that surround larger grains in a rock

Aphanitic:

the texture of plutonic or volcanic igneous rocks, with grains that are not visible to the naked eye.

Luster

the way light interacts with the surface of a crystal, rock, or mineral

Felsic

those with between 45 and 55 percent silica are mafic

Intermediate

those with between 55 and 65 percent silica are intermediate;