Rocks and Shit Flashcards
Isotope
. Two atoms of the same element with a different number of neutrons in the nucleus
Mineral
An element or chemical compound that is normally crystalline and is formed as the result of geologic processes`
Crystalline
Crystalline refers to the orderly regular repeating geometric patterns of atoms found in most minerals
weathering
the way that a mineral breaks down by physical and chemical processes at or near the surface of Earth, is important in forming sediments and soil
Quartz.
a form of silicon dioxide (SiO2) with a network structure of silicon–oxygen tetrahedra, is one of the most abundant minerals in the crust of Earth.
Feldspars.
Feldspars are aluminosilicates, containing silicon (Si), oxygen (O), and aluminum (Al) in combination with potassium (K), sodium (Na), or calcium (Ca) in a network structure of silicon–oxygen tetrahedra. The most abundant group of rock-forming minerals, constituting 60 percent of Earth’s crust, feldspars are commercially important in the ceramics and glass industries. They are generally gray or pink and are fairly hard (Figure 3.7b).
Mica.
Mica is a name for a group of important rock-forming minerals formed from sheets of silicon– oxygen tetrahedra, including the colorless mica, muscovite, KAl2(AlSi3)O10(OH)2, and the ferromagnesian mica, biotite, defined below. The micas are distinguished by a perfect basal cleavage—that is, they cleave parallel to the base of the crystal and peel into sheets. The mineral muscovite was used in pioneer times as window material and later in doors of ovens, enabling one to see what was cooking.
Ferromagnesian Minerals
Ferromagnesian minerals are a group of silicates in which the silicon and oxygen combine with iron (Fe) and magnesium (Mg).
Clay
The term clay is an important term in environmental geology and can be defined in several ways. We use the term clay-sized particles to describe particles that are less than 0.004 mm in diameter—very small indeed. We also refer to clay as very fine mineral fragments defined in terms of chemical composition and internal crystal structure. The numerous clay minerals may be classified into several groups, based on chemical characteristics and atomic structure. Some clays take in a lot of water and expand upon wetting, a topic discussed in Chapter 17.
Oxides
Earth materials containing useful minerals, especially metals, that can be extracted at a profit are called ores
Magnetite
also known as lodestone, is a natural magnet that attracts and holds iron particles
Carbonate Minerals.
This mineral is the major constituent of limestone and marble, two very important rock types. . Many marine organisms, from oysters and clams to forminifera have shells composed of carbonate minerals. Chemical weathering of such rocks by water dissolves the calcite, often producing caverns, sinkholes, or surface pits
Sulfide Minerals.
Pyrite (iron sulfide, FeS2 ), also known as fool’s gold, is a sulfide mineral and is shown in Figure 3.7f. Sulfides can also be associated with environmental degradation, which typically occurs when roads, tunnels, or mines cut through coal-bearing rocks that contain sulfide minerals.
Native Elements.
Minerals formed of a single element are called native elements; gold, silver, copper (Figure 3.7g), and diamonds are examples of native elements.
rock
A rock is an aggregate of one or more minerals.
rock cycle
a worldwide rock-recycling system linking subsurface processes driven by Earth’s internal heat, which melts or changes rocks in the tectonic cycle, to surface processes driven by solar energy.
law of crosscutting relationships
a rock is younger than any other rock that it cuts
law of original horizontality
states that when originally deposited, sedimentary layers are nearly horizontal.
law of superposition
states that if a series of layered sediments have not been overturned, the oldest layers are on the bottom and the youngest are on top.
Igneous rocks
have crystallized from magma, a mobile mass of hot, quasi-liquid Earth material consisting of a mixture of melted and solid materials. Magma is often generated in the upper asthenosphere or the lithosphere
Intrusive Igneous Rocks
If magma cools slowly and crystallizes well below the surface of Earth, the result is intrusive igneous rock
Batholiths and Plutons
The largest intrusions are called batholiths, which are composed of a series of smaller intrusions known as plutons. Plutons are variable in size but may be as small as a few kilometers in width. Some intrusions, such as dikes and sills, are tabular in form, relatively long and narrow (Figure 3.17). Dikes intrude through and cut across existing rocks, whereas sills intrude parallel to the rock layers. Most dikes we observe in the field are relatively small, less than 1 m to a few meters in width. Dikes can form complex patterns that either cut across one another or are in a radial pattern; these patterns are known as dike swarms
