Rocks - Key terms
A mixture of two or more metals.
A process of consolidation whereby particles of sediment are cemented together, usually with mud.
A substance made up of atoms of more than one element, chemically bonded to one another.
Unconsolidatedrock material containing rocks ranging in size from very small clay (less than 0.00015 in., or 0.004 mm) to boulders (defined as any rock larger than 10 in., or 0.254 m). Sedimentary rock often appears in the form of conglomerate.
A process whereby materials become compacted, or experience an increase in density. This takes place through several processes, including recrystallization and cementation.
A type of solid in which the constituent parts have a simple and definite geometric arrangement that is repeated in all directions.
The process wherebysediment is laid down on the Earth's surface.
A term referring to all the changes experienced by a sediment sample under conditions of low temperature and low pressure followingdeposition. Higher temperature and pressure conditions may lead to metamorphism.
A substance made up of only one kind of atom. Unlike compounds, elements cannot be broken chemically into other substances.
The movement of soil and rock as the result of forces produced bywater, wind, glaciers, gravity, and other influences. In most cases, a fluid medium, such as air or water, is involved.
One of the three principal types of rock, along with sedimentary and metamorphic rock. Igneous rock is formed by the crystallization of molten materials, for instance, in a volcano or other setting where plate tectonicprocesses take place.
Molten rock at or near the surface of the earth that becomes igneousrock. Below the surface, lava is known as magma.
Molten rock beneath the surface of the earth that becomes igneousrock. Once it is at or near the surface, magma is known as lava.
A naturally occurring, typically inorganic substance with a specific chemical composition and a crystalline structure.
An area of geology devoted to the study of minerals. Mineralogy includes several subdisciplines, such ascrystallography, the study of crystal formations within minerals.
A substance with a variable composition, meaning that it is composed of molecules or atoms of differing types in varying proportions.
A rock or mineral possessing economic value.
At one time, chemists used the term organic only in reference to living things. Now the word is applied to most compounds containing carbon and hydrogen, thus excluding carbonates (which are minerals), and oxides such as carbon dioxide.
An area of geology devoted to the study of rocks, including their physical properties, distribution, and origins.
In the context of chemistry, precipitation refers to the formation of a solid from a liquid.
The formation of new mineral grains as a result of changes in temperature, pressure, or other factors.
An aggregate of minerals or organic matter, which may be consolidated or unconsolidated.
The ongoing process whereby rocks continually change from one type to another, typically through melting, metamorphism, uplift, weathering, burial, or other processes.
A term that can have several meanings. The sand at a beach could be a variety of unconsolidated materials, though most likely it is silica (SiO 2 ). Sand is also a term used for a size of rock ranging from very fine to very coarse.
Material deposited at or near Earth's surface from a number of sources, most notably preexisting rock.
One of the three major types of rock, along with igneous and metamorphic rock. Sedimentary rock usually is formed by the deposition, compaction, and cementation of rock that has experienced weathering. It also may be formed as a result of chemical precipitation.
Rock that appears in the form of loose particles, such as sand.
A process whereby the surface of Earth rises, owing to either a decrease in downward force or an increase in upward force.
The breakdown of rocks and minerals at or near the surface of Earth as the result of physical, chemical, or biological processes.