![Inclusions2-1](https://upload.wikimedia.org/wikipedia/commons/8/89/Inclusions2-1.jpg)
In
mineralogy, an inclusion is any material that is trapped inside a
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. Rafferty, ed. (2 ...
during its formation. In
gemology
Gemology or gemmology is the science dealing with natural and artificial gemstone materials. It is a geoscience and a branch of mineralogy. Some jewelers (and many non-jewelers) are academically trained gemologists and are qualified to identif ...
, an inclusion is a characteristic enclosed within a gemstone, or reaching its surface from the interior.
According to
Hutton's law of inclusions, fragments included in a host rock are older than the host rock itself.
Mineralogy
Inclusions are usually other minerals or
rock
Rock most often refers to:
* Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids
* Rock music, a genre of popular music
Rock or Rocks may also refer to:
Places United Kingdom
* Rock, Caerphilly, a location in Wales ...
s, but may also be water, gas or
petroleum
Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...
. Liquid or
vapor
In physics, a vapor (American English) or vapour (British English and Canadian English; see spelling differences) is a substance in the gas phase at a temperature lower than its critical temperature,R. H. Petrucci, W. S. Harwood, and F. G. Her ...
inclusions are known as
fluid inclusions image:Inclumed.gif, 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, ...
. In the case of
amber
Amber is fossilized tree resin that has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects."Amber" (2004). In ...
it is possible to find insects and plants as inclusions.
The analysis of atmospheric gas
bubble
Bubble, Bubbles or The Bubble may refer to:
Common uses
* Bubble (physics), a globule of one substance in another, usually gas in a liquid
** Soap bubble
* Economic bubble, a situation where asset prices are much higher than underlying funda ...
s as inclusions in
ice cores is an important tool in the study of
climate change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
.
A
xenolith
A xenolith ("foreign rock") is a rock fragment ( country rock) that becomes enveloped in a larger rock during the latter's development and solidification. In geology, the term ''xenolith'' is almost exclusively used to describe inclusions in ig ...
is a pre-existing rock which has been picked up by a lava flow.
Melt inclusions
A melt inclusion is a small parcel or "blobs" of melt(s) that is entrapped by crystals growing in magma and eventually forming igneous rocks. In many respects it is analogous to a fluid inclusion within magmatic hydrothermal systems. Melt inclusio ...
form when bits of melt become trapped inside crystals as they form in the melt.
Gemology
![Three Phase in Rock Crystal Quartz, Pakistan](https://upload.wikimedia.org/wikipedia/commons/2/2f/Three_Phase_in_Rock_Crystal_Quartz%2C_Pakistan.jpg)
Inclusions are one of the most important factors when it comes to gem valuation. In many gemstones, such as
diamonds
Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the chemically stable form of carbon at room temperature and pressure, bu ...
, inclusions affect the
clarity
Clarity may refer to:
Arts, entertainment, and media Fictional entities
* Clarity, a magic spell in the online game ''EverQuest''
* Clarity, a fictional drug from the film '' Minority Report''
Music Albums
* ''Clarity'' (Jimmy Eat World album)
...
of the gem, diminishing the value. In some gems, however, such as
star sapphires, the inclusion actually increases the value of the gem.
Many colored gemstones 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 gems include gems with very little or no inclusions. They include
aquamarines
Aquamarine is a pale-blue to light-green variety of beryl. The color of aquamarine can be changed by heat.
Aquamarine has a chemical composition of Be3Al2Si6O18, also containing Fe2+. It has a hardness of 7.5 to 8. Aquamarine contains no or few ...
,
topaz and
zircon
Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of t ...
.
*Type II colored gems include those that often have a few inclusions. They include
sapphire
Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide () with trace amounts of elements such as iron, titanium, chromium, vanadium, or magnesium. The name sapphire is derived via the Latin "sa ...
,
ruby
A ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum ( aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called ...
,
garnet
Garnets () are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives.
All species of garnets possess similar physical properties and crystal forms, but differ in chemical composition. The different s ...
and
spinel
Spinel () is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula in the cubic crystal system. Its name comes from the Latin word , which means ''spine'' in reference to its pointed crystals.
Properties
S ...
.
*Type III colored gems include those that almost always have inclusions. Gems in this category include
emerald and
tourmaline
Tourmaline ( ) is a crystalline silicate mineral group in which boron is compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is a gemstone and can be found in a wide variety of colors.
The te ...
.
File:Gem with inclusion.JPG, Clear gemstone with metallic inclusion.
File:Peridotgem.JPG, Peridot with milky inclusion.
File:Ruby gem.JPG, Natural ruby with inclusions.
Metallurgy
The term "inclusion" is also used in the context of metallurgy and metals processing. During the melt stage of processing particles such as oxides can enter or form in the liquid metal which are subsequently trapped when the melt solidifies. The term is usually used negatively such as when the particle could act as a fatigue crack
nucleator or as an area of high stress intensity.
See also
*
Diamond inclusions
References
{{reflist
Mineralogy
Petrology
Gemology
Metallurgy