Aninclusion inmineralogy is any material trapped inside amineral during its formation. Ingemology, it is an object enclosed within a gemstone or reaching its surface from the interior.[1] According toJames Hutton's law of inclusions, fragments included in a host rock are older than the host rock itself.[2][3] The term is also used inmetallurgy.
Inclusions are usuallyrocks or other minerals, less often water, gas orpetroleum. Liquid andvapor createfluid inclusions. Inamber, insects and plants are common inclusions.
The analysis of atmospheric gasbubbles as inclusions inice cores is an important tool in the study ofclimate change.[4]
Axenolith is a preexisting rock which has been picked up by a lava flow.Melt inclusions form when bits of melt become trapped inside crystals as they form in the melt.
Inclusions are one of the most important factors when it comes to gem valuation. They diminish theclarity and value of many gemstones, such asdiamonds, and increase the value of others, such asstar sapphires.[5]
Many colored gemstones are expected to have inclusions which do not greatly affect their values. They are categorized into three types:[2]
Inclusions are also found inmetallurgy and metals processing.[6][7] 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 cracknucleator or as an area of high stress intensity.[8][9]
