Envir. Geo ch. 2 (Rocks & Minerals - A First Look)
Terms
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- Atom
- smallest particle still retaining the chemical characteristics of an element
- nucleus
- center of an atom, with one or more protons and some neutrons (except in H); circled by electrons
- atomic mass number
- protons + neutrons
- isotopes
- same element, but diff atomic mass number b/c diff # of neutrons
- ion
- atom without an equal number of protons and electrons
- cation
- positively charged ion (lost electrons)
- anion
- negatively charged ion (gained electrons)
- ionic bond
- attraction between oppositely charged ions
- covalent bond
- atoms sharing electrons
- compounds
- atoms of different elements bond together in specific proportions
- mineral
- naturally ocurring, inorganic, solid element or compound with a specific chem. comp. and internal crystal structure
- mineral identification
- look at combo of color, hardness, cleavage, luster, density, magnetism
- silicates
- most abundant group of minerals; silicon, oxygen, probably other. Quartz, feldspars, ferromagnesians, micas, clays.
- sheet silicates
- micas and clays; weak bonds btwn sheets
- nonsilicates
- carbonates, sulfates, sulfides, oxides, native elements
- native elements
- nonsilicate single elements, e.g. gold, silver, diamond, copper
- rock
- solid, cohesive aggregate of one or more minerals or glass
- igneous rocks
- formed by solidification and crystalization of cooling magma
- plutonic igneous rocks
- magma cools slowly deep in the earth, forming big crystals
- volcanic igneous rocks
- lava flows to surface while still molten and cools quickly, forming few crystals, fine-grained (often on ocean floor)
- porphyry igneous rocks
- formed while magma moved toward surface, so big and little crystals
- general igneous rock characteristics
- tightly interlocking crystals, or crystals embedded in glass; angular rather than rounded crystals; little pore space; structurally strong
- sedimentary rocks
- formed by compaction/cementation of sediments
- lithification
- the set of processes transforming sediment into rocks
- clastic sedimentary rocks
- formed from products of other broken up rocks (lots of pore space)
- chemical sedimentary rocks
- from crystals formed by precipitation or growth from a solution (e.g. limestone, rock salt)
- metamorphic rocks
- formed from preexisting rock subjected to heat and pressure (rock is solid, but minerals break down, form, change shape)
- contact metamorphism
- heated by adjacent rising lava
- regional metamorphism
- pressure and heat from mountain-building or plate-tectonic movements
- foliation
- metamorphic texture formed by directed stretch, creating parallel stretched crystals
- schist
- a type of foliation
- gneiss
- a type of striated foliation