In
mineralogyMineralogy is an Earth Science focused around the chemistry, crystal structure, and physical properties of minerals. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their...
, an
inclusion is any material that is trapped inside a
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
during its formation.
In
gemologyGemology or gemmology is the science, art and profession of identifying and evaluating gemstones. It is considered a geoscience and a branch of mineralogy. Some jewelers are academically trained gemologists and are qualified to identify and evaluate gems.- Background :With further post-graduate...
, an inclusion is a characteristic enclosed within a gemstone, or reaching its surface from the interior.
According to
HuttonJames Hutton MD was a Scottish geologist, physician, naturalist, chemist and experimental farmer. He is considered the father of modern geology...
's law of inclusions, fragments included in a host rock are older than the host rock itself.
Inclusions are usually other minerals or
rockIn geology, rock is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
s, but may also be
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
,
gasThis page is about the physical properties of gas as a state of matter. For the uses of gases, and other meanings, see Gas .A gas is one of four states of matter. Near absolute zero, a substance exists as a solid...
or
petroleumPetroleum or crude oil is a naturally occurring, flammable liquid found in rock formations in the Earth consisting of a complex mixture of hydrocarbons of various molecular weights, plus other organic compounds.The term "petroleum" was first used in the treatise De Natura Fossilium, published in...
.
In
mineralogyMineralogy is an Earth Science focused around the chemistry, crystal structure, and physical properties of minerals. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their...
, an
inclusion is any material that is trapped inside a
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
during its formation.
In
gemologyGemology or gemmology is the science, art and profession of identifying and evaluating gemstones. It is considered a geoscience and a branch of mineralogy. Some jewelers are academically trained gemologists and are qualified to identify and evaluate gems.- Background :With further post-graduate...
, an inclusion is a characteristic enclosed within a gemstone, or reaching its surface from the interior.
According to
HuttonJames Hutton MD was a Scottish geologist, physician, naturalist, chemist and experimental farmer. He is considered the father of modern geology...
's law of inclusions, fragments included in a host rock are older than the host rock itself.
Mineralogy
Inclusions are usually other minerals or
rockIn geology, rock is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
s, but may also be
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
,
gasThis page is about the physical properties of gas as a state of matter. For the uses of gases, and other meanings, see Gas .A gas is one of four states of matter. Near absolute zero, a substance exists as a solid...
or
petroleumPetroleum or crude oil is a naturally occurring, flammable liquid found in rock formations in the Earth consisting of a complex mixture of hydrocarbons of various molecular weights, plus other organic compounds.The term "petroleum" was first used in the treatise De Natura Fossilium, published in...
.
LiquidLiquid is one of the principal states of matter. A liquid is a fluid that has the particles loose and can freely form a distinct surface at the boundaries of its bulk material. The surface is a free surface where the liquid is not constrained by a container....
or
vaporA vapor or vapour is a substance in the gas phase at a temperature lower than its critical temperature....
inclusions are known as
fluid inclusionsthumb|250px|Trapped in a time capsule the same size as the diameter of a human hair, the ore-forming liquid in this inclusion was so hot and contained so much dissolved solids that when it cooled, crystals of halite, sylvite, gypsum, and hematite formed. As the samples cooled, the fluid shrank more...
. In the case of
amberAmber is fossilized tree resin , which has been appreciated for its color and natural beauty since neolithic times. Good quality amber is used for the manufacture of ornamental objects and jewelry...
it is possible to find
insectInsects are arthropods, having a hard exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae. They are the most diverse group of animals on the planet and include more than a million species that are already described. Insects represent more than half of all...
s and
plantPlants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants,...
s as inclusions.
The analysis of atmospheric gas
bubble-Physical bubbles:* Liquid bubble, a globule of one substance encased in another, usually air in a liquid* Soap bubble, a bubble formed by soapy water* Antibubble, a droplet of liquid surrounded by a thin film of gas-Arts and literature:...
s as inclusions in
ice coreAn ice core is a core sample from the accumulation of snow and ice over many years that have re-crystallized and have trapped air bubbles from previous time periods...
s is an important tool in the study of
climate changeClimate change is a change in the statistical distribution of weather over periods of time that range from decades to millions of years. It can be a change in the average weather or a change in the distribution of weather events around an average...
.
Contrast with
xenolithA xenolith is a rock fragment which becomes enveloped in a larger rock during the latter's development and hardening. In geology, the term xenolith is almost exclusively used to describe inclusions in igneous rock during magma emplacement and eruption...
.
Gemology
Inclusions are one of the most important factors when it comes to gem valuation. In many gemstones, such as
diamondsThe diamond is one of the best-known and most sought-after gemstones. Diamonds have been known to humankind and used as decorative items since ancient times; some of the earliest references can be traced to India. Diamond's hardness and high dispersion of light make it useful for industrial...
, inclusions affect the
clarityDiamond clarity is a quality of diamonds relating to the existence and visual appearance of internal characteristics of a diamond called inclusions, and surface defects called blemishes. Clarity is one of the four Cs of diamond grading, the others being carat, color, and cut...
of the stone, diminishing the stone's value. In some stones, however, such as
star sapphireStar sapphire may mean several things.* Star Sapphire is a gemstone that exhibits a star-like phenomenon known as asterism .* Star Sapphire is the name of several DC Comics supervillains....
s, the inclusion actually increases the value of the stone.
Many colored gemstones, such as
amethystAmethyst is a violet variety of quartz often used in jewelry. The name comes from the Ancient Greek a- and methustos , a reference to the belief that the stone protected its owner from drunkenness; the ancient Greeks and Romans wore amethyst and made drinking vessels of it in the belief that it...
,
emeraldEmeralds are a variety of the mineral beryl colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5 - 8 on the 10 point Mohs scale of mineral hardness. Most emeralds are highly included, so their toughness is classified as generally poor...
, and
sapphireSapphire refers to gemstone varieties of the mineral corundum, an aluminium oxide , when it is a color other than red, in which case the gem would instead be a ruby. Trace amounts of other elements such as iron, titanium, or chromium can give corundum blue, yellow, pink, purple, orange, or...
, are expected to have inclusions, and the inclusions do not greatly affect the stone's value. Colored gemstones are categorized into three types as follows:
- Type I colored stones include stones with very little or no inclusions. They include aquamarine
Aquamarine may mean:* Aquamarine , a color, a shade between green and blue* A gemstone-quality blue berylAquamarine may also refer to:* Aqua Marine, a private housing estate in Hong Kong* Aquamarine , a 2001 novel by Alice Hoffman...
, topazTopaz is a silicate mineral of aluminium and fluorine with the chemical formula Al
2SiO
42. Topaz crystallizes in the orthorhombic system and its crystals are mostly prismatic terminated by pyramidal and other faces....
and zirconZircon is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate and its corresponding chemical formula is ZrSiO4. A common empirical formula showing some of the range of substitution in zircon is 1-x4x-y...
.
- Type II colored stones include stones that often have a few inclusions. They include sapphire
Sapphire refers to gemstone varieties of the mineral corundum, an aluminium oxide , when it is a color other than red, in which case the gem would instead be a ruby. Trace amounts of other elements such as iron, titanium, or chromium can give corundum blue, yellow, pink, purple, orange, or...
, rubyA ruby is a pink to blood-red gemstone, a variety of the mineral corundum . The red color is caused mainly by the presence of the element chromium. Its name comes from ruber, Latin for red. Other varieties of gem-quality corundum are called sapphires...
, garnetThe garnet group includes a group of minerals that have been used since the Bronze Age as gemstones and abrasives. The name "garnet" may come from either the Middle English word gernet meaning 'dark red', or the Latin granatus , possibly a reference to the Punica granatum , a plant with red seeds...
and spinelThe spinels are any of a class of minerals of general formulation A
2+B
23+O
42- which crystallise in the cubic crystal system, with the oxide anions arranged in a cubic close-packed lattice and the cations A and B occupying some or all of the...
.
- Type III colored stones include stones that almost always have inclusions. Stones in this category include emerald
Emeralds are a variety of the mineral beryl colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5 - 8 on the 10 point Mohs scale of mineral hardness. Most emeralds are highly included, so their toughness is classified as generally poor...
and tourmalineTourmaline is a crystal silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is classed as a semi-precious stone and the gem comes in a wide variety of colors...
.