Geological characteristics of brucite

According to the metallogenic geological conditions and geological characteristics of deposits, brucite deposits in China can be divided into two categories: ultrabasic rock brucite deposits and carbonate rock brucite deposits.


Ultrabasic rock type brucite deposit, namely fibrous brucite deposit, is located in the transition zone of tectonic units and is controlled by faults. For example, the heimulin brucite deposit in southern Shaanxi is actually a composite deposit of chrysotile asbestos and fibrous brucite. The deposit is divided into three ore belts from top to bottom, namely chrysotile asbestos belt, mixed ore belt and fibrous brucite belt. The fibrous brucite ore body is composed of lentils of different sizes. The ore body is mainly coarse reticulated fibrous brucite, and the surrounding rock of the vein body is serpentine. The single vein is several meters, tens of meters or even more than 100 meters long. The scale of ore veins depends on the size of tensile fractures. Often, multiple veins form a complex ore vein or ore belt, and multiple ore belts form the ore body. The mixed ore belt is composed of chrysotile asbestos and fibrous brucite. The ore belt is lenticular or irregular strip. The transverse chrysotile asbestos vein and longitudinal fibrous brucite vein are interspersed in the ore belt, and their contents are high and low. Such deposits are only distributed in southern Shaanxi.


Carbonate brucite deposits occur in stable platform areas, and the brucite deposits in Eastern Liaoning are typical representatives of this type. The ore bearing formations are Dashiqiao formation and Lieryu formation of Liaohe Group. Dashiqiao formation is mainly distributed in Liaodong Peninsula and extends northeast to Ji'an, Jilin Province. The rock assemblages are mainly magnesite marble, dolomite marble and marble. In addition to brucite, this group is also rich in magnesite, talc, Xiuyan Jade, diopside, tremolite and so on. Lieryu formation is distributed in Yingkou, Fengcheng, Kuandian to Ji'an, Jilin in a NE direction. The rock assemblages are mainly magnesite marble, biotite plagioclase granulite, shallow granulite, etc. Among them, many of the most important boron deposits in China form a boron ore belt. Brucite minerals are located in the roof and floor of boron ore, so the stratabound of brucite deposit is obvious. Magnesite marble and dolomite marble are its source beds. The deposit is distributed around the granite body, and the existence of rock mass is closely related to the formation of brucite. Brucite often forms a metallogenic system with magnesite, talc and other deposits. The shape of brucite ore body is irregular lenticular and layered, with a small output scale, ranging from a few meters to more than ten meters thick, extending by tens of meters to one or two hundred meters. The ore metasomatic relationship is clear, and the ore body is in a gradual transition relationship with the surrounding rock. Marble residuals of different sizes are common in the ore body, and brucite also exists in the residuals. The phenomenon of brucite metasomatic dolomite can also be seen under the microscope. These conditions are sufficient to explain that the formation of brucite deposit is closely related to hydrothermal metasomatism. According to the mineral composition and structure, brucite deposits can be divided into two natural types. One is massive brucite ore, which is white, grayish white and light yellow, with massive structure. Brucite is produced as microfiber or flake aggregate. The ore is mainly composed of brucite with a content of more than 90% and a small amount of gangue minerals, such as serpentine, dolomite, calcite, magnesite, etc. The chemical composition of the ore is relatively pure, and the MgO content is more than 60%. This ore is the most common type of ore. The second is flaky brucite ore, which is white, gray white and black gray. Brucite is produced with large crystals. The content of brucite in the ore is 30 ~ 70%, and there are many gangue minerals, including serpentine, calcite, dolomite, magnesite, talc, etc. the chemical composition of the ore is impure, and the content of MgO is less than 60%.