What are Inclusions? Classification of the genesis of inclusions

An inclusion is a rock that is wrapped within another rock, and the composition of the rock that is wrapped can be the same or different from the periphery. These are inclusions that can be seen with the naked eye. Some call it a captive body.

The genesis is that when the magma intrudes, the surrounding rock falls into the magma and is not completely assimilated and retained its original mineral composition, and the inclusions are characterized by a ring of baking edges around the periphery.

In addition, there are minerals encapsulated in crystals, which are also encapsulated by other minerals falling into the crystals during the process of crystal formation.

Inclusion, originally a term used in mineralogy, refers to a closed system in a mineral consisting of one or more phases of material with a phase boundary of the host mineral.

The material of the inclusion** can be a foreign material unrelated to the host mineral or a diagenetic or oreogenic medium identical to the host mineral. Inclusions come in a variety of shapes and sizes, including solid, liquid and gas, and a combination of these three phases. The inclusions contain the "mother liquor" of diagenesis and mineralization, so it is a precious sample for studying geological processes, which can objectively reflect the original appearance of geological history.

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In the vast majority of natural crystal necklaces or crystal balls, there will always be some defects in the inclusions, especially when they are immersed in water or raised, and the naked eye will see a small number of small cracks in the reflective surface or flocculent gas-liquid inclusions in some places of a few beads or crystal balls. In synthetic crystals, the inclusions have few roots, the interior is dry, and there are almost no defects.

Transparency natural crystal crystal crystal clear, the inside is clear, such as the faceted beaded necklace in the white porcelain basin filled with water, in addition to the periphery of each bead, the middle of the beads and the water are auspicious and clear, as if there is no sense of existence. Synthetic crystals are naturally transparent, but when they are placed in the water, the perimeter of the beads is clear, but the middle is not as clear as the surrounding water like natural crystal beads, and you can feel the presence of beads.

Hello, happy to answer your questions. Inclusions are divided into three types: primary, secondary, and pseudo-secondary according to their genesis. Primary inclusions are inclusions that are formed simultaneously during the growth of the main mineral.

They can often be distributed in clusters parallel to some crystallization directions of the main mineral, especially some plane directions of the parallel main mineral. Secondary inclusions are inclusions formed by the dissolution of the main minerals caused by the hydrothermal fluid entering the main minerals along the microcracks of the main minerals in the later stage after the formation of the main minerals, and the inclusions formed by the recrystallization process. Pseudo-secondary inclusions are inclusions formed when these parts are recrystallized due to the action of stress and tectonic activities in the crystallization process of the main minerals, which leads to the entry of the ore-forming solution and causes these parts to be recrystallized.

Because their distribution in the main minerals is very similar to secondary inclusions, they are called pseudo-secondary inclusions. Dear, it's a pleasure to serve you.

Inclusions are divided into three types: primary, secondary, and pseudo-secondary according to their genesis. Primary inclusions are bridge inclusions that are formed simultaneously during the growth of the primary mineral. They can often be parallel to certain crystallization directions of the host mineral (especially some of the crystal planes of the parallel host mineral.

direction) in clusters (Figs. 4-4). Secondary inclusions are the dissolution and recrystallization of the main mineral caused by the late hydrothermal fluid entering the main mineral along the micro-cracked volta-shaped slit of the main mineral after the formation of the main mineral.

Inclusions formed during the process. Pseudo-secondary inclusion is an inclusion formed when the main mineral is recrystallized due to the action of stress and tectonic activity, which causes the main mineral to crack and cause the ore-forming solution to enter, and causes these parts to recrystallize. Because their distribution in the main mineral is similar to secondary inclusions, they are called pseudosecondary inclusions.

Figure 4-4 Schematic diagram of the inclusion.

A, B, and C in the diagram indicate primary, secondary, and pseudosecondary inclusions, respectively.

According to Luo Gufeng. et al., 1993).

1.Vapor phase composition.

The results of inclusion freezing showed that the gas phase disappearance temperature of various types of inclusions in the mining area was concentrated in -59 -50, indicating that the gas phase composition was CO2

Mainly. Yuan et al. (1995) and Yang et al. (2001) also showed that the gas phase composition of various inclusions in different ore types and minerals in this area was CO2

It is mainly contained, and at the same time contains a small amount of CO and CH4

and n22Liquid-phase composition.

Although Yuan et al. (1995), Niu Hecai et al. (1996) and Yang et al. (2001) all analyzed the liquid-phase composition of the inclusions in this area, the results obtained were quite different due to the different analytical equipment, analytical methods and analysis objects, but the overall variation law of the liquid-phase composition was similar. In this section, the analysis results of Niu et al. (1996) are used to summarize the characteristics of the liquid phase composition of the inclusions in this area.

As can be seen from Table 8-1, the liquid phase composition of quartz inclusions in barite ores is Na+

Primary, followed by K+

and Ca2+Mg2+

The content is the lowest, of which Na+

The content is higher than K+

and ca2+ by an order of magnitude; Anions are more complex, cl-

The content is relatively high and also contains a certain amount.

and the liquid phase composition of quartz inclusions in F-calcite type ores with Na+

and Ca2+ dominantly, K+

Mg2+ is secondary; Anions.

Main, cl-

and f content is relatively low. These characteristics show that the ore-forming fluid in this area is generally Na+K+Cl-

There are certain differences in the ore-forming fluids of CO2H2O solution, barite shed clear stone ore and calcite ore. The results of Yuan et al. (1995) and Yang et al. (2001) also support this conclusion.

Table 8-1 Liquid phase composition (mol L) of the inclusion of Mianning rare earth deposits

According to Niu et al., 1996).

The pH value of the barite ore ore-forming fluid calculated according to the liquid-phase composition of the quartz inclusions is higher than that of deionized water (, indicating that the ore-forming fluid is a weakly alkaline fluid; The pH value of the calcite ore ore-forming fluid is also relatively higher than that of deionized water (, which also indicates that the ore-forming fluid is a weakly alkaline fluid.

According to the microscopic observation, the width of the inclusions of quartz minerals in the deposit may be divided into two categories: primary inclusions and secondary inclusions, with secondary inclusions being the main ones. Primary inclusions are often solitary and closed, elliptical, polygonal or irregular, and are often gas-liquid two-phase inclusions. The size of the inclusions is 10 to 15 m, and the gas-liquid ratio is between 10% and 35%.

Secondary inclusions are single-phase and two-phase, arranged along the fissure.