Evaporite

Classification：Sedimentary Rock

A rock type formed by evaporation and crystallization. Evaporite is mostly developed in lagoon. Its cause is hot climate and strong evaporation. Meanwhile, the influx of new low salinity brine is limited. But in many cases, the evaporite is replaced by bittern instead of the original mineral in rock. Salt rock and gypsum belong to the evaporite.

Evaporite is a kind of chemical sedimentary rock. From the evaporation and concentration of brine in the lake basin and the sea basin, salt substances are crystallized according to different solubility. The dry area of bay, lagoon and the continent is a favorable environment for the formation of Evaporite. It is mainly composed of chloride (stone salt, potassium salt, etc.), sulfate (halide, gypsum, etc.), nitrate (potassium, sodium, nitro, etc.) and borate (borax, etc.). It can be divided into gypsum and anhydrite, salt rock and potassium magnesite. Cambrian, Shiru Ki, Devonian and Permian are important Evaporite forming periods in the world. China is mainly composed of Triassic, Cretaceous and third periods. The most common salt minerals in Evaporite are natural soda, soda, Glauber's salt, Glauber's salt and Glauber's salt. Evaporite is an important mineral resource, widely used in agriculture and industry.

The most common salt minerals in Evaporite include natural alkali, soda, mirabilite, anhydrous mirabilite, Glauber's nitrate, gypsum, anhydrite, stone salt, purgate salt, halogenite, carnallite and potassium stone salt; in some Saline Lake, there are solid borax minerals or brine containing boron, bromine and iodine. Evaporite generally has crystalline structure and sometimes recrystallized into a mega crystal structure of several millimeters or even several centimeters. Generally, they are layered structures, and often appear brecciate and muddy secondary structures, forming salt solution breccia. The formation of Evaporite is due to the evaporation of water, the accumulation of metal ions and acid radicals under closed conditions. A basin of seawater is evaporated naturally in the sun. With the increase of salinity, the evaporative minerals, such as calcite, dolomite, gypsum, anhydrite and stone salt, will be crystallized. The main types of Evaporite are gypsum rock anhydrite, Glauber's salt mudstone, Shi Yanyan, halite and potassium halite. Because of the different chemical properties of land water and sea water in different regions or different diagenetic times (such as chloride, sulfate and mixed types), the modern Saline Lake and the salt deposits of different salts are produced. The chaghan Saline Lake in the Qaidam Basin, Qinghai, China has deposited carnallite deposits, and some of the Saline Lake in Qinghai and Tibet have boron deposits. There are abundant natural alkaloids in some modern Saline Lake in Inner Mongolia and Xinjiang. There is a solid potash salt deposit composed of potassium and stone salts in the Meng Ye well, Yunnan, China, but the reserves are very small. There are large reserves of potash salt deposits in Canada, the former Soviet Union and Germany, the supply of potash minerals in the world, and the ancient solid carnallite deposits in Thailand and Laos, and the ancient solid days found in the Wucheng of Henan in China. An alkali deposit. The underground brine related to the Saline Lake or the solid salt layer includes a variety of rare elements, such as boron, bromine, iodine, cesium and lithium, all of which have comprehensive utilization value. In the Saline Lake of Tibet, the sedimentary minerals containing lithium and cesium are found.
Evaporite can be used to extract sodium, make sodium salt, and also be used in the manufacture of chlorine and hydrochloric acid; potash is used as the farm manure; gypsum and anhydrite are used mainly as building materials, additives for making cement and papermaking filler; sodium sulfate, ammonium sulfate and sulphuric acid are made from mirabilite, and can be used in leather, papermaking, dyestuffs, man-made fibers, and medicine. Various sectors such as medicine and metallurgy; natural soda is used to make soda ash and caustic soda.