| Abrasives |
A substance (as emery or pumice)
used for abrading (to rub or wear away especially by friction) , smoothing,
or polishing |
| Amphibolite facies |
A rock made up mostly amphibole
including minerals like hornblende and plagioclase feldspar. |
| Anion |
A negatively charged atom (a
building block of matter; combination of protons, neutrons, and electrons
) or group of atoms produced by gain of electrons(fundamental particle of
matter, the most elementary unit of negative electrical charge.) |
| Anthracite |
A very hard, black coal; has
the highest carbon content and heating value; extremely shiny and black,
may have a slight golden shine; low density |
| Aphanitic |
An igneous rock texture in
which individual mineral grains are too small to be distinguished with the
naked eye. |
| Ash |
Fine particles of volcanic
rock and glass blown into the atmosphere by a volcanic eruption. |
| Augite |
Dark-green to black glassy
mineral of the pyroxene group containing large amounts of aluminum and iron
and magnesium |
| Banded |
Alternating bands of light
and dark-colored minerals |
| Basaltic |
A dark, fine-grained, extrusive
(volcanic) igneous rock with a low silica content (40% to 50%), but rich
in iron, magnesium and calcium. Generally occurs in lava flows, but also
as dikes. Basalt makes up most of the ocean floor and is the most abundant
volcanic rock in the Earth's crust. |
| Batholith |
Very large mass of intrusive
(plutonic) igneous rock that forms when magma solidifies at depth. A batholith
must have greater than 100 square kilometers (40 square miles) of exposed
area. |
| Bed |
One of several parallel layers
of rock arranged one on top of another; one of a series of layers |
| Biotite |
A common rock-forming mineral
of the mica family. Biotite is a black or dark brown silicate rich in iron,
magnesium, potassium, aluminum, and silica. Like other micas, it forms flat
book-like crystals that peel apart into individual sheets on cleavage planes. |
| Bituminous |
A harder, more compacted, black
coal; Bituminous coal has even more carbon than lignite coal and a correspondingly
higher heating value. |
| Blueschist facies |
Metamorphic rock rich in bluish
colored amphibole. |
| Bond |
an attractive force that holds
together the atoms, ions, or groups of atoms in a molecule or crystal. |
| Borate |
Containing the elements of
boron and oxygen |
| Borate minerals |
Most borate minerals are found
in a type of sedimentary rock that is called an evaporate which is formed
by precipitation. |
| Borax |
A white crystalline compound
that consists of a hydrated sodium borate Na2B4O7·10H2O, that occurs as
a mineral or is prepared from other minerals, and that is used especially
as a flux, cleansing agent, and water softener, as a preservative, and as
a fireproofing age |
| Boron |
A trivalent metalloid element
found in nature only in combination and used in metallurgy and in composite
structural materials; Pure boron is a little-used dark powder, but boron
compounds are important in many industries such as glass and detergent manufacture
and agriculture. |
| Burial metamorphism |
A form of regional metamorphism
that acts on rocks covered by 5 to 10 kilometers of rock or sediment, caused
by heat from the Earth's interior and pressure. |
| Caldera |
Large, generally
circular, fault-bounded depression caused by the withdrawal of magma from
below a volcano or volcanoes. Commonly, the magma erupts explosively as
from a giant volcano and, falling back to Earth as volcanic ash, fills the
caldera so formed. |
| Carbon |
A nonmetallic
element found native (in the form of diamond and graphite) or as a component
of organic compounds |
| Carbonates |
The carbonate
rocks make up 10 to 15% of sedimentary rocks. They largely consist of two
types of rocks. Limestones which are composed mostly of calcite (CaCO3)
or high Mg calcite [(Ca,Mg)CO3], and Dolostones which are composed mostly
of dolomite [CaMg(CO3)2] Carbonates include the radical "CO3" which reacts
with acids to produce carbon dioxide. |
| Carboniferous
period |
Between 350 and
300 million years ago, (pre-dinosaurs)much of the world was covered with
luxuriant vegetation growing in swamps,leaving a deposit with a high percentage
of carbon. |
| Cataclastic |
Metamorphism caused
along a fault. Any rock produced by mainly along fault zones. When stress
exceeds breaking strength, a rock yields by rupture. The rock may break
as a unit, or individual minerals may be selectively granulated. |
| Cement |
A kind of limestone,
or a mixture of clay and lime, for making mortar which will harden under
water. |
| Cementation |
Chemical, physical, and biological changes
which sediments are converted to rock through deposition or precipitation
of minerals in the spaces between grains.
 cements:
quartz and calcite
|
| Chatoyant |
Having a changeable
luster or color with an undulating narrow band of white light |
| Chemical families |
Geologists classify
minerals into chemical families based on their compositions. They are divided
into classes depending on the anion or positive radical that is part of
their chemical formula. These include oxides, sulfides, sulfates, carbonates,
silicates, borates, and halides. There are some additional groups. |
| Chemical sedimentary
rocks |
Sedimentary rock
composed of minerals that were precipitated from water. This process begins
when water traveling through rock dissolves some of the minerals, carrying
them away from their source. Eventually these minerals are redeposited,
or precipitated, when the water evaporates away or when the water becomes
over-saturated. |
| Chemical weathering |
The process that
changes the chemical makeup of a rock or mineral at or near the Earth's
surface. Chemical weathering alters the internal structure of minerals by
the removing and/or adding elements. |
| Chlorite |
Family of platy
silicate minerals containing various amounts of magnesium, iron, aluminum,
water, and small amounts of other elements. Chorites are considered part
of the mica family because the crystals form small flakes. Commonly green. |
| Cinder |
A bubbly (vesicular)
volcanic rock fragment that forms when molten, gas-filled lava is thrown
into the air, then solidifies as it falls. |
| Clastic |
A sedimentary
rock composed of fragments or sediments of pre-existing rock or fossils. |
| Clastic sedimentary
rocks |
A rock composed
of pieces of preexisting rock, cemented together |
| Cleavage |
The tendency of
a mineral to split along planes determined by the crystal structure; also
: the occurrence of such splitting; a fragment (as of a diamond) obtained
by splitting |
| Climatic |
Of or pertaining
to seasonal weather patterns |
| Color |
the shade or appearance
of a substance; sensation of the eye resulting from stimulation of retina
by light waves of certain lengths |
| Conchoidal fracture |
A mineral's habit
of fracturing to produce curved surfaces like interior of a shell (conch).
Typical of glass and quartz. |
| Concrete |
Concrete is basically
a mixture of two components: aggregates and a cementing agent. The paste,
usually comprised of Portland cement and water, binds the aggregates (sand
and gravel or crushed stone) into a rocklike mass as the cement hardens
because of the chemical reaction of the cement and water. |
| Contact metamorphism |
Metamorphism caused
by heat from an igneous intrusion including sills, dikes. And other plutons. |
| Converge |
A boundary between
two plates of the Earth's crust that are pushing together. |
| Convergent |
Tending to come
together from different directions |
| Core |
The innermost
layer of the Earth, made up of mostly of iron and nickel. The core is divided
into a liquid outer core and a solid inner core. The core is the most dense
of the Earth's layers. |
| Country rock |
Rocks that were
pre-existing. An igneous rocks will squeeze itself through country rocks.. |
| Cross bedding |
Cross bedding refers to sedimentary layer deposited
at an angle to an underlying set of beds.
|
| Crown |
The top of a gemstone |
| Crystal form |
Geometrical form
taken by a mineral, giving external expression to orderly internal atomic
arrangement. |
| Crystalline |
Having a crystal
structure; When referring to sedimentary rocks, crystalline designates a
texture in which mineral crystals have formed in an interlocking pattern
|
| Crystallization |
Growth of minerals
(crystalline solids) from a liquid. |
| Current |
The portion of
a stream or body of water, which is moving with a velocity much greater
than the average of the rest of the water. |
| Debris |
A type of landslide made up
of a mixture of water-saturated rock debris and soil with a consistency
similar to wet cement. Debris flows move rapidly downslope under the influence
of gravity. Sometimes referred to as earth flows or mud flows. |
| Decomposition |
To break up by chemical processes |
| Deformation |
General term for folding, faulting,
and other processes resulting from shear, compression, and extension of
rocks. |
| Density |
The quantity per unit volume,
unit area, or unit length: as a : the mass of a substance per unit volume
b : the distribution of a quantity (as mass, electricity, or energy) per
unit usually of space (as length, area, or volume) |
| Deposit |
Any accumulation of sediment. |
| Deposition |
The natural process of laying
down rock layers |
| Depositional |
An act or process of depositing |
| Dike |
A sheet-like or tabular-shaped
igneous intrusion that cuts across the sedimentary layering, metamorphic
foliation, or other texture of a pre-existing rock. |
| Diverge |
To extend from a common point
in different directions; move or draw apart |
| Divergent |
A boundary in which two tectonic
plates move apart. |
| Facets |
The cut face of a gemstone |
| Feldspar |
Family of silicate minerals
containing varying amounts of potassium, sodium and calcium along with aluminum,
silicon and oxygen.. Feldspar crystals are stubby prisms, generally white,
gray, or pink. |
| Fiber optic |
Fiber optic (or "optical fiber")
refers to the medium and the technology associated with the transmission
of information as light impulses along a glass or plastic wire or fiber.
Fiber optic wire carries much more information than conventional copper
wire and is far less subject to electromagnetic interference. Most telephone
company long-distance lines are now fiber optic. |
| Fissures |
Elongate, narrow fractures. |
| Flanks |
The side of a volcano. |
| Fluid |
Capable of flowing and easily
changing shape |
| Foliation |
Aligned layers of minerals
characteristic of some metamorphic rocks. Foliation forms in metamorphic
rocks when pressure squeezes flat or elongates minerals so that they become
aligned. These rocks develop a platy or sheet-like structure that reflects
the direction that pressure was applied. |
| Formation |
A rock formation is a body
of rock of considerable extent with distinctive characteristics that allow
geologists to map, describe, and name it. |
| Fossiliferous
sedimentary rocks |
Sedimentary rocks that contains
fossils. |
| Fracture |
As mineral characteristic,
way in which mineral breaks when it does not have cleavage. May be conchoidal
(shell shaped), fibrous, hackly, or uneven. |
| Fresco |
The art of painting on freshly
spread plaster, before it dries. |
| Garnet |
Family of silicate minerals
containing varying amounts of aluminum, iron, magnesium, and calcium. Schist
and gneiss often have tiny, glassy red garnet crystals. |
| Gem |
A precious or sometimes semiprecious
stone cut and polished for ornament that has value |
| Gemologist |
A person who studies gemstones |
| Geode |
Roughly spherical, hollow or
partially hollow rock lined with crystals that project toward hollow center.
Crystals, often perfectly formed, are usually quartz although calcite and
dolomite are also found |
| Girdle |
A girdle is measured all the way around the outline
of the diamond, and must be uniform and fall into thin to slightly thick.
Girdle thickness outside of this range can either lead to damage, or add
additional weight and cause difficulty in setting.
|
| Glaciers |
Permanent body of ice, consisting
largely of recrystallized snow, that shows evidence of downslope or outward
movement due to the stress of its own weight. |
| Glassy texture |
Resembling glass in its properties,
as in smoothness, brittleness, or transparency |
| Gneiss |
A coarse-grained, foliated
metamorphic rock that commonly has alternating bands of light and dark-colored
minerals. |
| Granoblastic |
A texture of roughly equidimensional
grains formed by the mutual adjustment of grain boundaries in the solid
state. |
| Granulite facies |
In rocks of basaltic composition,
the granulite results from progressive dehydration of amphibolites at high
temperature. |
| Greenschist facies |
The name comes from the abundance
of the green mineral chlorite in such rocks. These rocks normally show a
highly developed foliation and often exhibit strong metamorphic differentiation.
|
| Halides |
Compound made from a halogen,
such as chlorine, iodine, bromine, or fluorine. |
| Halite |
A mineral; rock salt or common
salt, NaCl. Occurs widely disseminated or in extensive beds and irregular
masses precipitated from seawater and interstratified with rocks of other
types as true sedimentary rock. |
| Hardness |
Mineral's resistance to scratching
on a smooth surface. Mohs scale of relative hardness consists of 10 minerals,
each scratching all those below it in scale and being scratched by all those
above it: 1-talc, 2-gypsum, 3-calcite, 4-flurite, 5-apatite, 6-orthoclase,
7-quartz, 8-topaz, 9-corundum, 10-diamond. |
| Horizontal beds |
Thick piles of loose gravel,
sand, silt, and mud become layered into flat laying beds. |
| Hornblende |
Amphibole family of silicate
minerals forming prism or needle like crystals; generally containing iron,
magnesium, calcium and aluminum in varying amounts, along with water. Hornblende
always has aluminum and is a most common dark green to black variety of
amphibole. Actinolite has no aluminum; it and is needle-shaped and light
green. |
| Hornfels |
A dark, very fine-grained metamorphic
rock produced by the recrystallization of a fine-grained rock by heat from
a nearby igneous intrusion. From the German, meaning horn rock. |
| Hornfels facies |
This facies develops around
contact metamorphisms. High temperatures with low pressures. |
| Magma |
Molten rock. Magma may be completely
liquid or a mixture of liquid rock, dissolved gases and crystals. Molten
rock that flows out onto the Earth's surface is called lava. |
| Magma chambers |
A body of molten rock and solid
crystal mush beneath the Earth's surface. When this chamber cools and solidifies,
it is called a pluton. |
| Magnetism |
Magnetism is the force where
objects are attracted or repelled to one another. Usually these objects
are metals containing cobalt, iron, or nickel |
| Mantle |
The layer of the Earth below
the crust and above the core. The uppermost part of the mantle is rigid
and, along with the crust, forms the 'plates' of plate tectonics. The mantle
is made up of dense, iron and magnesium rich (ultramafic) rock such as dunite
and peridotite. |
| Marble |
A metamorphic rock of made
of calcium carbonate. Marble forms from limestone by metamorphic recrystallization. |
| Marine |
Of or relating to the sea |
| Matrix |
Fine-grained material surrounding
larger grains in a sedimentary rock. |
| Mesozoic era |
An era of geological history
comprising the interval between the Permian and the Tertiary or the corresponding
system of rocks that was marked by the presence of dinosaurs, marine and
flying reptiles, ammonites, ferns, and gymnosperms and the appearance of
angiosperms, mammals, and birds |
| Metallic |
of, relating to, or being
a metal; made of or containing a metal |
| Metamorphic |
A rock that has undergone chemical
or structural changes produced by increase in heat or pressure, or by replacement
of elements by hot, chemically active fluids. |
| Metamorphism |
A process whereby rocks undergo
physical or chemical changes or both to achieve equilibrium with changing
conditions. Agents of metamorphism are heat, pressure, and chemically active
fluids. |
| Metamorphosed |
The process by which conditions
within the Earth, below the zone of diagenesis, alter the mineral content,
chemical composition, and structure of solid rock without melting it. Igneous,
sedimentary, and metamorphic rocks may all undergo metamorphism |
| Mica |
Group of silicate minerals
composed of varying amounts of aluminum, potassium, magnesium, iron and
water. All micas form flat, plate-like crystals. Crystals cleave into smooth
flakes. Biotite is dark, black or brown mica; muscovite is light-colored
or clear mica. |
| Mineral |
A natural, inorganic crystalline
material |
| Mineralogy |
A science dealing with minerals
, their crystallography, properties, classification, and the ways of distinguishing
them |
| Mohs hardness
scale |
The ten-point scale of mineral
hardness , keyed arbitrarily to the minerals 1-talc, 2-gypsum, 3-calcite,
4-flurite, 5-apatite, 6-orthoclase, 7-quartz, 8-topaz, 9-corundum, 10-diamond. |
| Mollusk |
Invertebrate having a soft
unsegmented body usually enclosed in a shell |
| Monolith |
A single stone, especially
one of large size, shaped into a pillar, statue, or monument |
| Mudstone |
A very fine-grained sedimentary
rock formed from mud |
| Muscovite |
One of the mica family of minerals.
Muscovite is light-colored or clear mica |
| Pavilion |
Measured from the girdle to
the point; bottom portion of a faceted gem |
| Pegmatites |
A form of igneous rock consisting
of extremely coarse granite resulting from the crystallization of magma
rich in rare elements. |
| Percolates |
To pass through fine interstices;
to filter; as, water percolates through porous stone |
| Phaneritic |
An igneous rock texture in
which the mineral grains are large enough to be seen with the unaided eye
and are of approximately equal size. |
| Phyllite |
A foliated metamorphic rock
that develops from shate and is marked by a silky sheen and medium grain
size. |
| Physical weathering |
The disintegration of materials
in which no new minerals or substances are formed |
| Placer deposits |
A concentration of relatively
heavy and resistant minerals in stream or beach deposits; two examples are
some deposits of gold and of diamonds. |
| Pluton |
A large body of intrusive igneous
rock that solidified within the crust. Batholiths and stocks are types of
plutons. |
| Plutonic |
Rock formed by slow crystallization,
which yields coarse texture. Once believed to be typical of crystallization
at great depth, but not a necessary condition; any igneous rock that cools
beneath the surface. (=intrusive rock). |
| Polymers |
A chemical compound or mixture
of compounds formed by polymerization (a chemical reaction in which two
or more molecules combine to form larger molecules that contain repeating
structural units )and consisting essentially of repeating structural units |
| Pores |
A minute opening or passageway;
an interstice between the constituent particles or molecules of a body;
as, the pores of stones. |
| Porphyritic |
An igneous rock texture characterized
by larger crystals (phenocrysts) in a matrix of distinctly finer crystals
(groundmass). |
| Positive radical |
An ion with a positive charge |
| Precipitate |
A mineral deposited from a
water solution in pores or other openings in rocks. Chemical reaction with
the surrounding rock, changes in pressure or temperature, or just drying
up (evaporation) can cause a mineral to precipitate out of solution. Quartz
veins are common products of mineral precipitation; The process that separates
solids from a solution. |
| Precipitation |
Discharge of water, in rain,
snow, hail, sleet, fog, or dew, on land or water surface. Also, process
of separating mineral constituents from solution by evaporation (halite,
anhydrite) or from magma to form igneous rocks; To precipitate from a solution
creating minerals |
| Pressure |
One of the main causes of metamorphism |
| Pyroclastic |
An igneous rock texture produced
from consolidation of fragmented volcanic material ejected during a violent
eruption. Also used to describe ash, bombs and other material forcefully
ejected during a volcanic eruption |
| Sand |
A type of clastic sediment
that is small, but larger than mud particles and smaller than pebbles |
| Sand dunes |
Landform made from wind blowing
on sand that makes ridges. Stronger winds make bigger dunes and lighter
winds make smaller dunes |
| Schist |
Metamorphic rock usually derived
from fine-grained sedimentary rock such as shale. Individual minerals in
schist have grown during metamorphism so that they are easily visible to
the naked eye. Schists are named for their mineral constituents. For example,
mica schist is conspicuously rich in mica such as biotite or muscovite. |
| Sedimentary |
Sedimentary rocks are 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. |
| Sedimentary environment |
A sedimentary environment is
an area of the Earth's surface where sediment is deposited. It can be distinguished
from other areas on the basis of its physical, chemical, and biological
characteristics. |
| Sedimentary rock |
Sedimentary rocks are formed
from pre-existing rocks, pieces of once-living organisms, or chemical means..
Sedimentary rocks often have distinctive layering or bedding. |
| Sedimentary structures |
Are those which form during
(or shortly after) deposition of the sediment. Some sedimentary structures
are created by the water or wind which moves the sediment. Other sedimentary
structures form after deposition - such as footprints, worm trails, or mudcracks. |
| Sedimentation |
The act of depositing sediments;
the deposition of the material of which sedimentary rocks are formed. |
| Sedimentologists |
The study of sedimentology
or the study of sedimentary rocks. |
| Seduction |
Process of one crustal plate
sliding down and below another crustal plate as the two converge. The subduction
zone is the area between the two plates, somewhat like a giant reverse fault. |
| Semimetals |
an element (as arsenic) possessing
metallic properties in an inferior degree and not malleable |
| Serpentinite |
A family of silicate minerals
rich in magnesium and water, derived from low-temperature alteration or
metamorphism of the minerals in ultramafic rocks. Rocks made up of serpentine
minerals are called serpentinite. Serpentine minerals are light to dark
green, commonly varied in hue, and greasy looking; the mineral feels slippery. |
| Shale |
Sedimentary rock derived from
mud. Commonly finely laminated (bedded). Particles in shale are commonly
clay minerals mixed with tiny grains of quartz eroded from pre-existing
rocks. |
| Shearing |
Stress that slices rocks into
parallel blocks that slide in opposite directions along their adjacent sides.
Shearing stress may be caused by transform motion. |
| Silicates |
A salt or ester derived from
a silicic acid; especially : any of numerous insoluble often complex metal
salts that contain silicon and oxygen in the anion, constitute the largest
class of minerals, and are used in building materials (as cement, bricks,
and glass) |
| Sill |
A sheet-like or tabular-shaped
igneous intrusion that cuts across the sedimentary layering, metamorphic
foliation, or other texture of a pre-existing rock. |
| Sillimanite |
Brown, pale green, or white
glassy silicate mineral that often occurs in long, slender, needlelike crystals
frequently found in fibrous aggregates. |
| Siltstone |
A sedimentary rock made mostly
of silt-sized grains. (Silt -loose particles of rock or mineral (sediment)
that range in size from 0.002 - 0.0625 millimeters in diameter. Silt is
finer than sand, but coarser than clay.) |
| Slate |
A fine-grained, foliated metamorphic
rock that develops from shale and tends to break into thin, flat sheets. |
| Sorting |
The range of grain sizes in
a sedimentary rock. |
| Specific gravity |
The ratio of the density of
a material to the density of water. |
| Stalactites |
A calcite mineral deposit which
hangs downwards from a roof or wall of a cave. |
| Stalagmites |
A cylinder of calcium carbonate
projecting upward from the floor of a limestone cave |
| Staurolite |
A silicate mineral that is
common in metamorphic rocks. Short prismatic crystals, some cross shaped,
reddish to dark brown |
| Stones |
A general term for all rocks
and minerals. |
| Streak |
The color of a mineral in its
powdered form, usually obtained by rubbing the mineral against an unglazed
porcelain tile to see the mark it makes. A mineral harder than the tile
must be pulverized by crushing. |
| Stress |
The force acting on a rock
or another solid to deform it, |
| Subducting |
Process of one crustal plate
sliding down and below another crustal plate as the two converge. |
| Sulfates |
Metal ions combine with the
Sulfate ion (SO4), atomic structure sometimes can allow bonding of water
molecules - Gypsum (plaster)-Barite (drilling mud) |
| Sulfides |
Mineral formed by direct union
of element with sulfur. Examples: argentite, chalcocite, galena, sphalerite,
pyrite, and cinnabar. |
| Symmetry |
The property of being symmetrical;
especially : correspondence in size, shape, and relative position of parts
on opposite sides of a dividing line or median plane or about a center or
axis |