Minerals Flashcards
anhydrite
a granular, white, anhydrous (water-lacking) calcium sulfate (CaSO4).
Andesite
A volcanic rock that in chemical composition is intermediate between basalt and granite.
Aragonite
A calcium carbonate mineral (CaCO3) that differs from calcite in its crystal form. (Aragonite is orthorhombic rather than rhombohedral as in calcite.)
Augite
A complex aluminous silicate of calcium, iron and magnesium, crystallising in the monoclinic system, and occurring in many igneous rocks, particularly those of basic composition. It is an essential component of basalt, dolerite and gabbro.
Basalt
Highly mafic igneous volcanic rock, typically fine-grained and dark in color; rough volcanic equivalent of gabbro.
Bowen’s Reaction Series
the sequence in which minerals crystallize from a cooling basaltic magma.
Calcite
The crystalline form of calcium carbonate, showing trigonal symmetry and a great variety of mineral habits. It is one of the commonest of minerals in association with both igneous and sedimentary rocks.
Carbonate clasts
sand or gravel sized pieces of carbonate. The most common clasts are either bioclasts (skeletal fragment of marine invertebrates) or ooids (Fig 4-39 C), which are spherical grains formed by the precipitation of carbonate around a nucleus.
Carbonate spar
clear, crystalline (sparry) carbonate. It occurs between clasts as a cement.
Chert
A dense, hard sedimentary rock or mineral composed of sub microcrystalline quartz. Unless colored by impurities, chert is white, as opposed to flint, which is dark or black.
Chlorite
A group of allied minerals which may be regarded as hydrated silicates of aluminium, iron and magnesium. They crystallise in the monoclinic system and are green in colour. They occur as alteration products of such minerals as biotite and hornblende, and also in schistose rocks.
Clastic sediment
sediment consisting of broken or eroded pieces of pre-existing rocks or minerals.
Clay mineral
silicates of hydrogen,aluminum,magnesium,iron, and potassium. Their basic structure is similar to that of mica but individual flakes are extremely small (some are as small as viruses). This means their mica-like form can be seen only with an electron microscope (Fig 4-15). Clay minerals form as a result of weathering of other aluminosilicate minerals, such as feldspars.
Cleavage
the tendency of a mineral to break evenly along one or more bright, planar surfaces.
Color
A mineral’s most conspicuous characteristic.
Coal
black, soft rock made of carbon. Coal originates from the compressed, lithified remains of dead leaves, stems and trunks of plants that grew in a swampy environment.
Contact metamorphism
metamorphism caused by heat from a nearby igneous intrusion. Contact metamorphic rocks are generally not foliated.
Continuous series
Because the plagioclase minerals maintain the same basic crystal structure but change continuously in their content of calcium and sodium, the right side of the diagram is called the continuous series.
Crystal habit
the way a mineral has grown by means of regular additions of ions to its surfaces from a liquid solution, a gas or molten rock.
Density
Its mass per unit volume (density=mass/volume). Density is a reflection of the relative “heaviness” of a mineral
Diorite
A relatively coarse-grained intrusive rock containing less silica than granite or granodiorite. It is composed primarily of plagioclase feldspar.
Discontinuous series
The left side of the diagram depicts reactions that result in minerals of distinctly different structure. It is therefore called the discontinuous series.
Dolomite
Either the magnesium-bearing carbonate mineral CaMg(CO3)2 or the rock that is composed largely of that mineral.
Evaporite
water-soluble, mineral sediments that result from the evaporation of bodies of surface water.
Extrusive igneous rock
mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff.
Feldspar
group of most common minerals of the Earth’s crust. All feldspars contain silicon, aluminum, and oxygen and may contain potassium, calcium and sodium.
Ferromagnesian silicate mineral
iron/magnesium bearing mineral, such as augite, hornblende, olivine or biotite.
Foliation
parallel alignment of textural and structural features of a rock.
Fractional crystallization
The separation of components of a cooling magma by sequential formation of particular mineral crystals at progressively lower temperatures.
Gabbro
dark, coarse-grained, intrusive igneous rock chemically equivalent to basalt.
Garnet
metamorphic index mineral. Forms at middle to high temperatures and pressures.