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They are usually dark in color, owing to the abundance of ferro-magnesian silicates, of high specific gravity and liable to decomposition. For these reasons they have been defined as a melanocrate series (rich in the dark minerals ); and they are often accompanied by a complementary leucocrate series (rich in the white minerals feldspar and ...
In mineralogy, an inclusion is any material trapped inside a mineral during its formation. In gemology , it is an object enclosed within a gemstone or reaching its surface from the interior. [ 1 ] According to James Hutton 's law of inclusions, fragments included in a host rock are older than the host rock itself.
Hydrothermal ore minerals, which typically form from high temperature aqueous solutions, trap tiny bubbles of liquids or gases when cooling and forming solid rock. The trapped fluid in an inclusion preserves a record of the composition, temperature and pressure of the mineralizing environment. [1] An inclusion often contains two or more phases ...
A study of sodium-rich quartz-alkali feldspar—biotite gneiss granulite facies terrane in the Kerala Khondalite Belt near Manali in south India found that in situ leucosomes (light colored segregations) within the gneiss showed the development of garnet replacing the dark biotite. The study indicated localized melting or migmatization within ...
These are known as calcium–aluminium-rich inclusions or "CAIs", so named because they are dominantly composed of calcium- and aluminum-rich silicate and oxide minerals. Like many chondrites, Allende is a breccia , and contains many dark-colored clasts or "dark inclusions" which have a chondritic structure that is distinct from the rest of the ...
The melanosome is a dark, mafic mineral band formed in migmatite which is melting into a eutaxitic texture; often, this leads to the formation of granite. The melanosomes form bands with leucosomes, and in that context may be described as schlieren (color banding) or migmatitic.
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Mineral inclusions (poikiloblastic texture): [17] a mineral that is formed at a lower P-T condition is included in another mineral that is formed at a higher P-T condition. For example, in thin section examination, biotite crystal is included in a garnet grain, so biotite is considered to be formed at an earlier time.