
In
geology
Geology (from the Ancient Greek
Ancient Greek includes the forms of the Greek language
Greek ( el, label=Modern Greek
Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply as Greek ...

and
mineralogy
Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical mineralogy, optical) properties of minerals and mineralized artifact (archaeology), artifacts. Specific st ...

, a mineral or mineral species is, broadly speaking, a solid
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together by chemical bonds. A homonuclear molecule, m ...
with a fairly well-defined
chemical composition
{{Unreferenced, date=December 2017
Chemical composition refers to identity and number of the chemical element
Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements
In chemistry, an el ...
and a specific
crystal structure
In crystallography
Crystallography is the experimental science of determining the arrangement of atoms in crystalline solids (see crystal structure). The word "crystallography" is derived from the Greek language, Greek words ''crystallon'' "co ...

that occurs naturally in pure form.
[John P. Rafferty, ed. (2011): ]
Minerals
'; p. 1. In the series ''Geology: Landforms, Minerals, and Rocks''. Rosen Publishing Group.
The geological definition of mineral normally excludes compounds that occur only in living beings. However some minerals are often
biogenic
A biogenic substance is a product made by or of life forms. While the term originally was specific to metabolite compounds that had toxic effects on other organisms, it has developed to encompass any constituents, secretions, and metabolites of pl ...
(such as
calcite
Calcite is a carbonate mineral
Carbonate minerals are those mineral
In geology
Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid E ...

) or are
organic compound
In chemistry
Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during ...
s in the sense of chemistry (such as
mellite
Mellite, also called honeystone, is an unusual mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure t ...
). Moreover, living beings often synthesize inorganic minerals (such as
hydroxylapatite
Hydroxyapatite, also called hydroxylapatite (HA), is a naturally occurring mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a ...
) that also occur in rocks.
The concept of mineral is distinct from
rock
Rock most often refers to:
* Rock (geology)
A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its Chemical compound, chemical composition and the way in w ...
, which is any bulk solid geologic material that is relatively homogeneous at a large enough scale. A rock may consist of one type of mineral, or may be an
aggregate of two or more different types of minerals, spacially segregated into distinct
phases.
Some natural solid substances without a definite crystalline structure, such as
opal
Opal is a hydrate
In chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, comp ...

or
obsidian
Obsidian (; ) is a naturally occurring volcanic glass formed when lava extrusive rock, extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock.
Obsidian is produced from felsic lava, rich in the lighter element ...

, are more properly called
mineraloid
A mineraloid is a naturally occurring mineral-like substance that does not demonstrate crystallinity. Mineraloids possess chemical compositions that vary beyond the generally accepted ranges for specific minerals. For example, obsidian is an amorp ...
s.
[Austin Flint Rogers and Paul Francis Kerr (1942): ]
Optical mineralogy
', 2nd ed., p. 374. McGraw-Hill; If a chemical compound occurs naturally with different crystal structures, each structure is considered a different mineral species. Thus, for example,
quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tetrahedra, ...

and
stishovite
Stishovite is an extremely hard, dense tetragonal form ( polymorph) of silicon dioxide
Silicon dioxide, also known as silica, is an oxide
of rutile. Ti(IV) centers are grey; oxygen centers are red. Notice that oxygen forms three bonds to titani ...

are two different minerals consisting of the same compound,
silicon dioxide
Silicon dioxide, also known as silica, is an oxide
of rutile. Ti(IV) centers are grey; oxygen centers are red. Notice that oxygen forms three bonds to titanium and titanium forms six bonds to oxygen.
An oxide () is a chemical compound that con ...
.
The
International Mineralogical Association
Founded in 1958, the International Mineralogical Association (IMA) is an international group of 40 national societies. The goal is to promote the science of mineralogy
Mineralogy is a subject of geology
Geology (from the Ancient Greek γῆ, ...
(IMA) is the generally recognized standard body for the definition and nomenclature of mineral species. , the IMA recognizes
5,762 official mineral species
out of 5,966 proposed or traditional ones.
The chemical composition of a named mineral species may vary somewhat by the inclusion of small amounts of impurities. Specific
varieties
Variety may refer to:
Science and technology
Mathematics
* Algebraic variety, the set of solutions of a system of polynomial equations
* Variety (universal algebra), classes of algebraic structures defined by equations in universal algebra
Hort ...
of a species sometimes have conventional or official names of their own.
For example,
amethyst
Amethyst is a violet (color), violet variety of quartz. The name comes from the Koine Greek αμέθυστος ''amethystos'' from α- ''a-'', "not" and μεθύσκω (Ancient Greek) / μεθώ (Modern Greek), "intoxicate", a reference to ...

is a purple variety of the mineral species
quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tetrahedra, ...

. Some mineral species can have variable proportions of two or more
chemical elements
In chemistry
Chemistry is the scientific
Science () is a systematic enterprise that builds and organizes knowledge
Knowledge is a familiarity or awareness, of someone or something, such as facts
A fact is an occurrence ...

that occupy equivalent positions in the mineral's structure; for example, the formula of
mackinawite
Mackinawite is an iron
Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic ...
is given as , meaning , where ''x'' is a variable number between 0 and 9. Sometimes a mineral with variable composition is split into separate species, more or less arbitrarily, forming a
mineral groupIn geology and mineralogy, a mineral group is a set of mineral species with essentially the same crystal structure and composed of chemically similar elements.Stuart J. Mills, Frédéric Hatert, Ernest H. Nickel, and Giovanni Ferraris (2009): "The st ...
; that is the case of the silicates , the
olivine group
The mineral olivine () is a magnesium iron Silicate minerals, silicate with the formula (magnesium, Mg2+, iron, Fe2+)2. It is a type of Nesosilicates, nesosilicate or orthosilicate. The primary component of the Earth's upper mantle (Earth), upper ...

.
Besides the essential chemical composition and crystal structure, the
description of a mineral species usually includes its common physical properties such as
habit
A habit (or wont as a humorous and formal term) is a routine of behavior
Behavior (American English
American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of t ...
,
hardness
Hardness (antonym: softness) is a measure of the resistance to localized plastic deformation
In engineering, deformation refers to the change in size or shape of an object. ''Displacements'' are the ''absolute'' change in position of a point ...
,
lustre,
diaphaneity, colour,
streak,
tenacity
Tenacity may refer to:
* Tenacity (psychology), having persistence in purpose
* Tenacity (mineralogy) describes a mineral's resistance to breaking, beading, cutting, or other forms of deformation.
* Mesotrione, Tenacity (herbicide), a brand name fo ...
,
cleavage
Cleavage may refer to:
Science
* Cleavage (crystal), in mineralogy and materials science, a process of splitting a crystal
* Cleavage (geology), the foliation perpendicular to stress as a result of ductile deformation
* Cleavage (embryo), in embr ...
,
fracture
Fracture is the separation of an object or material into two or more pieces under the action of stress (physics), stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the ...
, parting,
specific gravity
Relative density, or specific gravity, is the ratio
In mathematics, a ratio indicates how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemon ...
,
magnetism
Magnetism is a class of physical attributes that are mediated by magnetic field
A magnetic field is a vector field
In vector calculus and physics, a vector field is an assignment of a vector to each point in a subset of space. For in ...

,
fluorescence
Fluorescence is the emission of light
Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that is visual perception, perceived by the human eye. Visible light is usually defined as ha ...

,
, as well as its taste or smell and its reaction to
acid
An acid is a or capable of donating a (hydrogen ion H+) (a ), or, alternatively, capable of forming a with an (a ).
The first category of acids are the proton donors, or s. In the special case of , proton donors form the H3O+ and are ...
.
Minerals are classified by key chemical constituents; the two dominant systems are the Dana classification and the Strunz classification.
Silicate mineral
Silicate minerals are rock-forming mineral
In geology
Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology) ...
s comprise approximately 90% of the
Earth's crust
350px, Plates in the crust of Earth
Earth's crust is a thin shell on the outside of Earth, accounting for less than 1% of Earth's volume. It is the top component of the lithosphere, a division of Earth's layers that includes the Crust (geology), ...
. Other important mineral groups include the
native elements,
sulfides
Sulfide (British English
British English (BrE) is the standard dialect of the English language
English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon England, early medieval England, whi ...
,
oxides
An oxide () is a chemical compound
A chemical compound is a chemical substance
A chemical substance is a form of matter
In classical physics and general chemistry, matter is any substance that has mass and takes up space by having vol ...
,
halides
A halide is a binary phase, of which one part is a halogen
The halogens () are a group in the periodic table consisting of five chemically related elements: fluorine
Fluorine is a chemical element with the Chemical symbol, symbol F and ato ...
,
carbonates
In chemistry, a carbonate is a salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in its natural form as a crystallinity, crystalline min ...
,
sulfates
The sulfate or sulphate ion is a polyatomic anion
An ion () is a particle, atom or molecule with a net electric charge, electrical charge.
The charge of the electron is considered negative by convention. The negative charge of an ion is ...
, and
phosphates
In chemistry
Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they un ...
.
Definitions
International Mineralogical Association
The
International Mineralogical Association
Founded in 1958, the International Mineralogical Association (IMA) is an international group of 40 national societies. The goal is to promote the science of mineralogy
Mineralogy is a subject of geology
Geology (from the Ancient Greek γῆ, ...
has established the following requirements for a substance to be considered a distinct mineral:
[E. H. Nickel & J. D. Grice (1998): "The IMA Commission on New Minerals and Mineral Names: procedures and guidelines on mineral nomenclature". ''Mineralogy and Petrology'', volume 64, issue 1, pages 237–263. ]
# ''It must be a naturally occurring substance formed by natural geological processes'', on Earth or other extraterrestrial bodies. This excludes compounds directly and exclusively generated by human activities (
anthropogenic
Anthropogenic ("human" + "generating") is an adjective that may refer to:
* Anthropogeny, the study of the origins of humanity
Counterintuitively, anthropogenic may also refer to things that have been generated by humans, as follows:
* Human imp ...
) or in living beings (
biogenic
A biogenic substance is a product made by or of life forms. While the term originally was specific to metabolite compounds that had toxic effects on other organisms, it has developed to encompass any constituents, secretions, and metabolites of pl ...
), such as
tungsten carbide
Tungsten carbide (chemical formula
A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pa ...

,
urinary calculi
Kidney stone disease, also known as nephrolithiasis or urolithiasis, is when a calculus (medicine), solid piece of material (kidney stone) develops in the urinary tract. Kidney stones typically form in the kidney and leave the body in the urine s ...
,
calcium oxalate
left, Portion of CaC2O4·2H2O lattice, highlighting the connectivity of the oxalate ligand.(Carbon: black; Oxygen: red; Calcium: green)
Calcium oxalate (in archaic terminology, oxalate of lime) is a calcium
Calcium is a chemical element wit ...

crystals in plant tissues, and
seashell
A seashell or sea shell, also known simply as a shell, is a hard, protective outer layer usually created by an animal that lives in the sea. The shell is part of the body of the animal. Empty seashells are often found washed up on beach ...

s. However, substances with such origins may qualify if geological processes were involved in their genesis (as is the case of
evenkite, derived from plant material; or
, from
bat guano
Guano ( Spanish from qu, wanu) is the accumulated excrement of seabirds and bats. As a manure, guano is a highly effective fertilizer due to its exceptionally high content of nitrogen, phosphate, and potassium: key nutrients essential for pl ...
; or
alpersite, from mine tailings).
Hypothetical substances are also excluded, even if they are predicted to occur in currently inaccessible natural environments like the Earth's core or other planets.
# ''It must be a solid substance in its natural occurrence.'' A major exception to this rule is native
mercury
Mercury usually refers to:
* Mercury (planet)
Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman g ...

: it is still classified as a mineral by the IMA, even though crystallizes only below −39 °C, because it was included before the current rules were established. Water and
carbon dioxide
Carbon dioxide (chemical formula
A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

are not considered minerals, even though they are often found as
inclusions in other minerals; but
water iceWater ice could refer to:
*Ice
Ice is water
Water is an Inorganic compound, inorganic, Transparency and translucency, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constit ...

is considered a mineral.
# ''It must have a well-defined crystallographic structure''; or, more generally, an ordered atomic arrangement.
This property implies several
macroscopic
The macroscopic scale is the length scale on which objects or phenomena are large enough to be visible with the naked eye, without magnifying optical instruments. It is the opposite of microscopic
The microscopic scale (from , ''mikrós'', "sm ...
physical properties, such as crystal form, hardness, and cleavage.
[, pp. 13–14] It excludes
ozokerite
Ozokerite, Wasatch County, Utah
Ozokerite or ozocerite, archaically referred to as earthwax or earth wax, is a naturally occurring odoriferous mineral wax or paraffinParaffin may refer to:
Substances
* Paraffin wax, a white or colorless soft sol ...
,
limonite
Limonite () is an iron ore
Iron ores are rocks
A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its Chemical compound, chemical composition and the w ...

,
obsidian
Obsidian (; ) is a naturally occurring volcanic glass formed when lava extrusive rock, extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock.
Obsidian is produced from felsic lava, rich in the lighter element ...

and many other amorphous (non-crystalline) materials that occur in geologic contexts.
# ''It must have a fairly well defined chemical composition''. However, certain crystalline substances with a fixed structure but variable composition may be considered single mineral species. A common class of examples are
solid solution
A solid solution describes a family of materials which have a range of compositions (e.g. AxB1−x) and a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word "solution" is used to desc ...

s such as
mackinawite
Mackinawite is an iron
Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic ...
, (Fe, Ni)
9S
8, which is mostly a
ferrous
In chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds composed of atoms, mo ...

sulfide with a significant fraction of iron atoms replaced by
nickel
Nickel is a chemical element
In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elem ...

atoms.
Other examples include layered crystals with variable layer stacking, or crystals that differ only in the regular arrangement of vacancies and substitutions. On the other hand, some substances that have a continuous series of compositions, may be arbitrarily split into several minerals. The typical example is the
olivine
The mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. R ...

group (Mg, Fe)
2SiO
4, whose magnesium-rich and iron-rich end-members are considered separate minerals (
forsterite
Forsterite (Mg2SiO4; commonly abbreviated as Fo; also known as white olivine) is the magnesium-rich Endmember, end-member of the olivine solid solution series. It is Isomorphism (crystallography), isomorphous with the iron-rich end-member, fayalit ...

and
fayalite
Fayalite (Fe2SiO4; commonly abbreviated to Fa) is the iron
Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and gro ...

).
The details of these rules are somewhat controversial.
For instance, there have been several recent proposals to classify amorphous substances as minerals, but they have not been accepted by the IMA.
The IMA is also reluctant to accept minerals that occur naturally only in the form of
nanoparticle
A nanoparticle or ultrafine particle is usually defined as a particle of matter
In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched ...

s a few hundred atoms across, but has not defined a minimum crystal size.
[
Some authors require the material to be a stable or metastable solid at room temperature (25 °C).] However, the IMA only requires that the substance be stable enough for its structure and composition to be well-determined. For example, it has recently recognized meridianiite (a naturally occurring hydrate of magnesium sulfate
Magnesium sulfate or magnesium sulphate (in British English
British English (BrE) is the standard dialect
A standard language (also standard variety, standard dialect, and standard) is a language variety that has undergone substantial ...

) as a mineral, even though it is formed and stable only below 2 °C.
, 5,762 mineral species are approved by the IMA. They are most commonly named after a person, followed by discovery location; names based on chemical composition or physical properties are the two other major groups of mineral name etymologies. Most names end in "-ite"; the exceptions are usually names that were well-established before the organization of mineralogy as a discipline, for example galena
Galena, also called lead glance, is the natural mineral form of lead(II) sulfide
Lead is a chemical element
upright=1.0, 500px, The chemical elements ordered by link=Periodic table
In chemistry
Chemistry is the science, scienti ...

and diamond
Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. At Standard conditions for temperature and pressure, room temperature and pressure, another solid form of ...

.
Biogenic minerals
A topic of contention among geologists and mineralogists has been the IMA's decision to exclude biogenic crystalline substances. For example, Lowenstam (1981) stated that "organisms are capable of forming a diverse array of minerals, some of which cannot be formed inorganically in the biosphere."
Skinner (2005) views all solids as potential minerals and includes biominerals in the mineral kingdom, which are those that are created by the metabolic activities of organisms. Skinner expanded the previous definition of a mineral to classify "element or compound, amorphous or crystalline, formed through ''biogeochemical
Biogeochemistry is the Branches of science, scientific discipline that involves the study of the chemistry, chemical, physics, physical, geology, geological, and biology, biological processes and reactions that govern the composition of the natural ...
'' processes," as a mineral.
Recent advances in high-resolution genetics
Genetics is a branch of biology
Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, ...

and X-ray absorption spectroscopy
X-ray absorption spectroscopy (XAS) is a widely used technique for determining the local geometric and/or electronic structure of matter. The experiment is usually performed at synchrotron radiation facilities, which provide intense and tunabl ...
are providing revelations on the biogeochemical relations between microorganism
A microorganism, or microbe,, ''mikros'', "small") and ''organism
In biology
Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes ...
s and minerals that may shed new light on this question. For example, the IMA-commissioned "Working Group on Environmental Mineralogy and Geochemistry " deals with minerals in the hydrosphere
The hydrosphere (from Greek#REDIRECT Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece
Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is app ...
, atmosphere
An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a layer or a set of layers of gases surrounding a planet or other material body, that is held in ...

, and biosphere
The biosphere (from Greek#REDIRECT Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece
Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is ap ...
. The group's scope includes mineral-forming microorganisms, which exist on nearly every rock, soil, and particle surface spanning the globe to depths of at least 1600 metres below the sea floor
The seabed (also known as the seafloor, sea floor, or ocean floor) is the bottom of the ocean
The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth. and 70 kilometres into the stratosphere
The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere
The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphe ...

(possibly entering the mesosphere
The mesosphere (; from Greek#REDIRECT Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece
Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population i ...
).
Biogeochemical cycle
In ecology
Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Topics of interest include the bi ...
s have contributed to the formation of minerals for billions of years. Microorganisms can precipitate
In aqueous solution, precipitation is the process of transforming a dissolved substance
Substance may refer to:
* Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes
* Chemical substance, a material with a de ...
metals from solution
Solution may refer to:
* Solution (chemistry)
Image:SaltInWaterSolutionLiquid.jpg, upMaking a saline water solution by dissolving Salt, table salt (sodium chloride, NaCl) in water. The salt is the solute and the water the solvent.
In chemistry ...
, contributing to the formation of ore
ore – psilomelane
Psilomelane is a group name for hard black manganese oxides including hollandite and romanechite. Psilomelane consists of hydrous manganese
Manganese is a chemical element
Image:Simple Periodic Table Chart- ...

deposits. They can also catalyze
that utilizes a low-temperature oxidation catalyst to convert carbon monoxide to less toxic carbon dioxide
Carbon dioxide (chemical formula ) is a colorless gas with a density about 53% higher than that of dry air. Carbon dioxide molecules ...

the dissolution
Dissolution may refer to:
Arts and entertainment Books
* Dissolution (Forgotten Realms novel), ''Dissolution'' (''Forgotten Realms'' novel), a 2002 fantasy novel by Richard Lee Byers
* Dissolution (Sansom novel), ''Dissolution'' (Sansom novel), a 2 ...
of minerals.
Prior to the International Mineralogical Association's listing, over 60 biominerals had been discovered, named, and published. These minerals (a sub-set tabulated in Lowenstam (1981)) are considered minerals proper according to Skinner's (2005) definition. These biominerals are not listed in the International Mineral Association official list of mineral names; however, many of these biomineral representatives are distributed amongst the 78 mineral classes listed in the Dana classification scheme.
Skinner's (2005) definition of a mineral takes this matter into account by stating that a mineral can be crystalline or amorphous. Although biominerals are not the most common form of minerals, they help to define the limits of what constitutes a mineral proper. Nickel's (1995) formal definition explicitly mentioned crystallinity as a key to defining a substance as a mineral. A 2011 article defined icosahedrite, an aluminium-iron-copper alloy as mineral; named for its unique natural icosahedral symmetry
A regular icosahedron has 60 rotational (or orientation-preserving) symmetries, and a symmetry order of 120 including transformations that combine a reflection and a rotation. A regular dodecahedron
A regular dodecahedron or pentagonal dodec ...
, it is a quasicrystal
A quasiperiodic crystal
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all dire ...

. Unlike a true crystal, quasicrystals are ordered but not periodic.
Rocks, ores, and gems
A rock
Rock most often refers to:
* Rock (geology)
A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its Chemical compound, chemical composition and the way in w ...
is an aggregate of one or more minerals[, pp. 15–16] or mineraloids. Some rocks, such as limestone
Limestone is a common type of carbonate
In chemistry, a carbonate is a salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in its na ...

or quartzite
Quartzite is a hard, non-Foliation (geology), foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usu ...

, are composed primarily of one mineral – calcite
Calcite is a carbonate mineral
Carbonate minerals are those mineral
In geology
Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid E ...

or aragonite
Aragonite is a , one of the three most common naturally occurring of , (the other forms being the s and ). It is formed by biological and physical processes, including precipitation from marine and freshwater environments.
The of aragonite d ...

in the case of limestone, and quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tetrahedra, ...

in the latter case. Other rocks can be defined by relative abundances of key (essential) minerals; a granite
Granite () is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cool ...

is defined by proportions of quartz, alkali feldspar
Feldspars () are a group of rock-forming tectosilicate
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust.
...
, and plagioclase feldspar
. (unknown scale)
Plagioclase is a series of Silicate minerals#Tectosilicates, tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagiocla ...
. The other minerals in the rock are termed accessory minerals, and do not greatly affect the bulk composition of the rock. Rocks can also be composed entirely of non-mineral material; coal
Coal is a combustible
, Germany
)
, image_map =
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is a sedimentary rock composed primarily of organically derived carbon.
In rocks, some mineral species and groups are much more abundant than others; these are termed the rock-forming minerals. The major examples of these are quartz, the feldspar
Feldspars are a group of rock-forming aluminium
Aluminium (aluminum in and ) is a with the Al and 13. Aluminium has a density lower than those of other common , at approximately one third that of . It has a great affinity ...
s, the mica
Micas ( ) are a group of mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs natural ...

s, the amphibole
Amphibole () is a group of Silicate minerals, inosilicate minerals, forming prism or needlelike crystals, composed of double chain tetrahedron, tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their s ...

s, the pyroxene
The pyroxenes (commonly abbreviated to ''Px'') are a group of important rock-forming Silicate minerals#Inosilicates, inosilicate minerals found in many Igneous rock, igneous and metamorphic rock, metamorphic rock (geology), rocks. Pyroxenes have t ...
s, the olivine
The mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. R ...

s, and calcite; except for the last one, all of these minerals are silicates. Overall, around 150 minerals are considered particularly important, whether in terms of their abundance or aesthetic value in terms of collecting.[, p. 14]
Commercially valuable minerals and rocks, other than gemstones, metal ores, or mineral fuels, are referred to as industrial minerals
Industrial resources (minerals) are geological materials which are mined for their commercial value, which are not fuel (fuel minerals or mineral fuels
A fossil fuel is a fuel formed by natural processes, such as anaerobic decomposition of b ...
. For example, muscovite
Muscovite (also known as common mica, isinglass, or potash mica) is a hydrated phyllosilicate
Silicate minerals are rock-forming mineral
In geology
Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'' ...

, a white mica, can be used for windows (sometimes referred to as isinglass), as a filler, or as an insulator.
Ore
ore – psilomelane
Psilomelane is a group name for hard black manganese oxides including hollandite and romanechite. Psilomelane consists of hydrous manganese
Manganese is a chemical element
Image:Simple Periodic Table Chart- ...

s are minerals that have a high concentration of a certain element, typically a metal. Examples are cinnabar
Cinnabar () or cinnabarite (), from the grc, κιννάβαρι (), is the bright scarlet to brick-red form of mercury(II) sulfide
Mercury sulfide'', or mercury(II) sulfide is a chemical compound composed of the chemical elements mercury (el ...

(HgS), an ore of mercury; sphalerite
Sphalerite is a sulfide mineral
The sulfide minerals are a class of s containing (S2−) or (S22−) as the major . Some sulfide minerals are economically important as metal s. The sulfide class also includes the , the , the , the , the bi ...

(ZnS), an ore of zinc; cassiterite
Cassiterite is a tin
Tin is a chemical element
Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements
In chemistry, an element is a pure substance consisting only of atoms that al ...

(SnO2), an ore of tin; and colemanite
Colemanite (Ca2B6O11·5H2O) or (CaB3O4(OH)3·H2O) is a : borate minerals, borate mineral found in evaporite Deposition (geology), deposits of alkaline Lake, lacustrine environments. Colemanite is a secondary mineral that forms by alteration of b ...

, an ore of boron
Boron is a chemical element
In chemistry
Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behav ...

.
Gems
A gemstone (also called a fine gem, jewel, precious stone, or semi-precious stone) is a piece of mineral
In geology
Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Ea ...

are minerals with an ornamental value, and are distinguished from non-gems by their beauty, durability, and usually, rarity. There are about 20 mineral species that qualify as gem minerals, which constitute about 35 of the most common gemstones. Gem minerals are often present in several varieties, and so one mineral can account for several different gemstones; for example, ruby
A ruby is a pink-ish red to blood-red colored gemstone
A gemstone (also called a fine gem, jewel, precious stone, or semi-precious stone) is a piece of mineral
In geology and mineralogy, a mineral or mineral species is, broadly spea ...

and sapphire
Sapphire is a precious gemstone
A gemstone (also called a fine gem, jewel, precious stone, or semi-precious stone) is a piece of mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical c ...

are both corundum
Corundum is a crystal
A crystal or crystalline solid is a solid
Solid is one of the four fundamental states of matter (the others being liquid
A liquid is a nearly incompressible fluid
In physics, a fluid is a substance th ...

, Al2O3.[, pp. 14–15]
Etymology
The first known use of the word "mineral" in the English language
English is a West Germanic language of the Indo-European language family
The Indo-European languages are a language family
A language is a structured system of communication used by humans, including speech ( spoken language), g ...

(Middle English
Middle English (abbreviated to ME) was a form of the English language
English is a West Germanic language of the Indo-European language family
The Indo-European languages are a language family
A language is a structured sys ...
) was the 15th century. The word came from , from , mine, ore.[mineral]
entry in the Merriam-Webster online dictionary. Accessed on 2020-08-28.
The word "species" comes from the Latin ''species'', "a particular sort, kind, or type with distinct look, or appearance".
Chemistry
The abundance and diversity of minerals is controlled directly by their chemistry, in turn dependent on elemental abundances in the Earth. The majority of minerals observed are derived from the Earth's crust
350px, Plates in the crust of Earth
Earth's crust is a thin shell on the outside of Earth, accounting for less than 1% of Earth's volume. It is the top component of the lithosphere, a division of Earth's layers that includes the Crust (geology), ...
. Eight elements account for most of the key components of minerals, due to their abundance in the crust. These eight elements, summing to over 98% of the crust by weight, are, in order of decreasing abundance: oxygen
Oxygen is the chemical element
Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements
In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

, silicon
Silicon is a chemical element with the Symbol (chemistry), symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a Tetravalence, tetravalent metalloid and semiconductor. It is a member ...

, aluminium
Aluminium (aluminum in and ) is a with the Al and 13. Aluminium has a density lower than those of other common , at approximately one third that of . It has a great affinity towards , and of on the surface when exposed to air ...

, iron
Iron () is a chemical element
In chemistry
Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behav ...

, magnesium
Magnesium is a chemical element
upright=1.0, 500px, The chemical elements ordered by link=Periodic table
In chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science ...

, calcium
Calcium is a chemical element
In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elem ...

, sodium
Sodium is a chemical element
In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical eleme ...

and potassium
Potassium is a chemical element
In chemistry
Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, b ...

. Oxygen and silicon are by far the two most important – oxygen composes 47% of the crust by weight, and silicon accounts for 28%.[, pp. 4–7]
The minerals that form are those that are most stable at the temperature and pressure of formation, within the limits imposed by the bulk chemistry of the parent body. For example, in most igneous rocks, the aluminium and alkali metals (sodium and potassium) that are present are primarily found in combination with oxygen, silicon, and calcium as feldspar minerals. However, if the rock is unusually rich in alkali metals, there will not be enough aluminium to combine with all the sodium as feldspar, and the excess sodium will form sodic amphiboles such as riebeckite
Riebeckite is a sodium
Sodium is a chemical element
Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements
In chemistry, an element is a pure substance consisting only of atoms th ...

. If the aluminium abundance is unusually high, the excess aluminium will form muscovite
Muscovite (also known as common mica, isinglass, or potash mica) is a hydrated phyllosilicate
Silicate minerals are rock-forming mineral
In geology
Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'' ...

or other aluminium-rich minerals. If silicon is deficient, part of the feldspar will be replaced by feldspathoid minerals. Precise predictions of which minerals will be present in a rock of a particular composition formed at a particular temperature and pressure requires complex thermodynamic calculations. However, approximate estimates may be made using relatively simple rules of thumb
''Rule of thumb'' is an approximate method for doing something, based on practical experience rather than theory. This usage of the phrase can be traced back to the seventeenth century and has been associated with various Trade (occupation), trades ...
, such as the CIPW norm, which gives reasonable estimates for volcanic rock formed from dry magma.
The chemical composition may vary between end member species of a solid solution
A solid solution describes a family of materials which have a range of compositions (e.g. AxB1−x) and a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word "solution" is used to desc ...

series. For example, the plagioclase
Plagioclase is a series of tectosilicate
Silicate minerals are rock-forming mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition ...
feldspar
Feldspars are a group of rock-forming aluminium
Aluminium (aluminum in and ) is a with the Al and 13. Aluminium has a density lower than those of other common , at approximately one third that of . It has a great affinity ...
s comprise a continuous series from sodium
Sodium is a chemical element
In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical eleme ...

-rich end member albite
Albite is a . It is the sodium of the plagioclase series. It represents a plagioclase with less than 10% content. The pure albite endmember has the formula 38. It is a . Its color is usually pure white, hence its name from ''albus''. It is ...

(NaAlSi3O8) to calcium
Calcium is a chemical element
In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elem ...

-rich anorthite
Anorthite is the calcium
Calcium is a chemical element with the Symbol (chemistry), symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physic ...
(CaAl2Si2O8) with four recognized intermediate varieties between them (given in order from sodium- to calcium-rich): oligoclase
Oligoclase is a rock-forming mineral
In geology
Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology), rocks o ...
, andesine
Andesine is a silicate mineral
Silicate minerals are rock-forming mineral
In geology
Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the ...
, labradorite
Labradorite ((Ca, Na)(Al, Si)4O8) is a calcium-enriched feldspar
Feldspars are a group of rock-forming aluminium tectosilicate minerals, containing sodium, calcium, potassium or barium. The most common members of the feldspar group are the ' ...

, and bytownite
Bytownite is a calcium rich member of the plagioclase solid solution series of feldspar minerals with composition between anorthite and labradorite. It is usually defined as having between 70 and 90%Anorthite, An (formula: (Ca0.7-0.9,Na0.3-0.1) . Other examples of series include the olivine series of magnesium-rich forsterite and iron-rich fayalite, and the wolframite">l(A ...
. Other examples of series include the olivine series of magnesium-rich forsterite and iron-rich fayalite, and the wolframite series of manganese-rich hübnerite and iron-rich ferberite.
Chemical substitution and coordination polyhedra explain this common feature of minerals. In nature, minerals are not pure substances, and are contaminated by whatever other elements are present in the given chemical system. As a result, it is possible for one element to be substituted for another. Chemical substitution will occur between ions of a similar size and charge; for example, K