Inclusion (mineral)

An inclusion (Latin inclusio "inclusion ") is a mineral enclosed in a foreign substance (liquid, gas, petroleum, natural asphalt, or other mineral ). A distinction in mineralogy between primary inclusions, which were formed before the completion of the formation of crystals in interstices in the hydrothermal stage, and secondary inclusions, which arose only after the crystallization.

Among the most famous inclusions are mineral needles ( eg rutile needles ). These inclusions are formed when the mineral existing needles of another mineral be included (e.g., quartz), and the second crystal grows to the first round. Just quartz often contains small or larger inclusions, such as asphalt ( Stinkquarz ), hematite or the above rutile needles.

Inclusions can also grow simultaneously with the surrounding crystal. If the mother crystal temporarily stops growing, other minerals may deposed on it. If this continues to grow, he surrounds the newly formed crystals, which are preserved as inclusions in the host crystal.

Inclusions of gas or liquid ( fluid pockets ) are, when they have been incorporated during crystal growth to the primary inclusions. If they get in until after the completed growth through cracks and fractures in the crystal (partly also by the decomposition of trapped minerals), it is called secondary inclusions.

Often, the gas or liquid bubbles are not very large with a diameter of less than 0.1 mm. By inclusions conclusions regarding the formation of the crystals may be considered, for example via the formation of temperatures and conditions.

If small inclusions occur in large quantities, this can lead to phenomena of light. Examples include tiger eye or labradorite. Here the quartz Replace another mineral ( pseudomorphs ), but does not grow in its normal crystal form, but in the already grown form of the former mineral.

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