Mineralogy

thumb|upright=1.25|Crystals of serandite, [[natrolite, analcime, and aegirine from Mont Saint-Hilaire, Quebec, Canada]]

thumb|upright=1.1|Group of precious and semiprecious stones—both uncut and faceted—including (clockwise from top left) diamond, uncut synthetic [[sapphire, ruby, uncut emerald, and amethyst crystal cluster.]]

thumb|upright=1.5|Mineralogy applies principles of chemistry, [[geology, physics and materials science to the study of minerals]]

qualitative ordinal scale characterizing scratch resistance of various minerals

thumb|upright=1.25|Examining a pink sapphire under a gemmological microscope Gemology or gemmology is the science dealing with natural and artificial gemstone materials. It is a specific interdisciplinary branch of mineralogy. Some jewelers (and many non-jewelers) are academically trained gemologists and are qualified to identify and evaluate gems.

ability of a solid material to exist in more than one form or crystal structure

color of the powder produced when a mineral specimen is dragged across an un-weathered surface

class of space groups, lattices, point groups, or crystals

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thumb|Pleochroism of cordierite shown by rotating a polarizing filter on the lens of the camera thumb|Pleochroism of tourmaline shown by rotating a polarizing filter on the lens of the camera

two separate crystals sharing some of the same crystal lattice points in a symmetrical manner

thumb|upright=0.5|Fulgurite

thumb|Quartz-filled geode, shown from inside (top) and outside (bottom)

thumb|A cobble (geology)|cobble encrusted with [[halite precipitated from the Dead Sea, Israel (with Israeli ₪1 coin [diameter 18mm] for scale)]]

chemical solution in solid form; whose solvent's crystal structure is not altered by solute

thumb|Concretions in Torysh, Western [[Kazakhstan]] thumb|Concretions with lens shape from island in Vltava river, Prague, Czech Republic thumb|Marlstone aggregate concretion, [[Sault Ste. Marie, Michigan, United States]] A concretion is a hard and compact mass formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular shapes also occur. The word concretion is borrowed from Latin , itself derived from concrescere , from con- and crescere .

shape and texture of the surface formed when a mineral is fractured

manner in which light interacts with a crystal, rock, or mineral's surface

Sapropel (a contraction of Ancient Greek words sapros and pelos, meaning putrefaction and mud (or clay), respectively) is a term used in marine geology to describe dark-coloured sediments that are rich in organic matter. Organic carbon concentrations in sapropels commonly exceed 2 wt.% in weight.

any material trapped inside a mineral during its formation

scientific organization promoting mineralogy

scheme for categorizing minerals

thumb|Pseudomorph of goethite after [[pyrite ]] thumb|Silica pseudomorph after [[gypsum crystals and silicified serpulid polychaete tubes]]

A mineraloid is a naturally occurring substance that resembles a mineral, but does not demonstrate the crystallinity of a mineral. Mineraloid substances possess chemical compositions that vary beyond the generally accepted ranges for specific minerals, for example, obsidian is an amorphous glass and not a true crystal; lignite (jet) is derived from the decay of wood under extreme pressure underground; and opal is a mineraloid substance because of its non-crystalline nature. Pearl is a mineraloid substance because the calcite crystals and the aragonite crystals are bonded by an organic material

primitive cell of crystal lattices with Voronoi decomposition applied

thumb|300px|Thorium concentrations on the Moon, as mapped by [[Lunar Prospector. Thorium correlates with the location of KREEP.]] KREEP, an acronym built from the letters K (the atomic symbol for potassium), REE (rare-earth elements) and P (for phosphorus), is a geochemical component of some lunar impact breccia and basaltic rocks. Its most significant feature is somewhat enhanced concentration of a majority of so-called "incompatible" elements (those that are concentrated in the liquid phase during magma crystallization) and the heat-producing elements, namely radioactive uranium, thorium, an

thumb|right|Tiger's eye thumb|right|Tiger's eye

The sclerometer, also known as the Turner-sclerometer (from meaning "hard"), is an instrument used by metallurgists, material scientists and mineralogists to measure the scratch hardness of materials. It was invented in 1896 by Thomas Turner (1861–1951), the first Professor of metallurgy in Britain, at the University of Birmingham.

type of crystal structure

thumb|right|lampworking|Lampworked [[dichroic glass bead]] In optics, a dichroic material refers to: a material which causes visible light to be split up into two distinct beams of different wavelengths (colours), one of which is reflected and one of which is transmitted (not to be confused with dispersion), or a material in which light rays having different polarization directions are absorbed differently.

base of crystal structure

after a first nucleation, second step of crystallization consisting in the regular accretion of atoms or ions at the surface of the crystal

thumb|Azurite-[[malachite on gossan from Arizona]] thumb|Malachite on gossan from Australia Gossan (eiserner hut or eisenhut) is intensely oxidized, weathered or decomposed rock, usually the upper and exposed part of an ore deposit or mineral vein. In the classic gossan or iron cap all that remains is iron oxides and quartz, often in the form of boxworks (which are quartz-lined cavities retaining the shape of the dissolved ore minerals). In other cases, quartz and iron oxides, limonite, goethite, and jarosite, exist as pseudomorphs, replacing the pyrite and primary ore minerals. Frequently, g

mountain in Canada

knot, mass, or lump of a mineral or mineral aggregate with a contrasting composition

stone of peat that did not turn into coal

crystal not bounded by its own crystal faces

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crystal whose faces are easily distinguishable

variety of natural processes that alter the composition of a rock

manufacturing process of synthetic gemstones

non-professional study of rocks

tool used to direct stream of gas

award of the Mineralogical Society of America

An endmember (also end-member or end member) in mineralogy is a mineral that is at the extreme end of a mineral series in terms of purity of its chemical composition. Minerals often can be described as solid solutions with varying compositions of some chemical elements, rather than as substances with an exact chemical formula. There may be two or more endmembers in a group or series of minerals.

in geology, process resulting in the formation of minerals

liquid and/or gas trapped within a crystal

Metamictisation (sometimes called metamictization or metamiction) is a natural process resulting in the gradual and ultimately complete destruction of a mineral's crystal structure, leaving the mineral amorphous. The affected material is therefore described as metamict.

linear furrow in rock generated from fault movement

thumb|upright|Crystalline copper "feather" from Itauz Mine, Kazakhstan, an example of a photo from the Mindat database.

mineral used in geology to determine the degree of metamorphism a rock has experienced

empirical rule resembling the rule of mixtures

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mineral variety of a IMA-CNMNC valid mineral species

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factor used to determine the compatibility of an ion with a crystal structure

mass of crystals or rock particles or soil particles

Pyrognomic materials are said to become visibly incandescent at relatively low temperatures. In practice, virtually all solid or liquid substances start to visibly incandesce around 798 K (525 °C; 977 °F), with a mildly dull red color, whether or not a chemical reaction takes place that produces light as a result of an exothermic process. This limit is called the Draper point. The incandescence does not vanish below that temperature, but it is too weak in the visible spectrum to be perceivable. Pyrognomic materials are thought to visibly incandesce at much lower temperatures than the

thumb|Adularescence in a moonstone cabochon, [[Minas Gerais, Brazil. The specimen's diameter is .]]