Salt is an indispensable condiment in our daily life. As early as the Yanhuang period, the ancients in China began to cook salt with seawater, which has a history of 5,000 years. At that time, these salts were not really salt, and the ancients called them "halogen".
With the continuous progress of society, people gradually learned how to separate salt crystals from brine, and crude salt was born. In the late Tang dynasty, the salt-making technology was further improved, and the crude salt could be removed to extract refined salt, which is what we call salt.
Due to the lack of exploration and drilling technology in ancient times, salt was mainly eaten from the sea and lakes. However, with the development of the times, the source of salt is no longer limited to the sea and lakes, but gradually extends to rock formations and minerals. According to the source of raw materials, salt can be divided into four categories: sea salt, lake salt, well salt and mineral salt.
Basic introduction of lake salt
Green salt is a kind of lake salt crystal of halite salt family, which is extracted directly from salt lake brine and dried in salt field. It mainly contains sodium chloride, trace elements of silicon, iron and aluminum, major elements of calcium and magnesium, and trace elements of manganese, titanium and strontium. It can be used as raw materials for edible salt, food preservative, alkali production, hydrochloric acid and chlorine, and can also be used for extracting metallic sodium.
Qinghai is known as the "world of salt", in which the world-famous Qarhan salt mine has a stone salt reserve of 43 billion tons, and the potassium salt reserve accounts for 97% of the total reserves in China. It is an important chemical raw material used in food. The content of sodium chloride is above 96%, which has the characteristics of pure salt taste.
According to their colors, there are blue salt, white salt, red salt and black salt. There are pearl salt, glass salt, coral salt, crystal salt, snowflake salt, vermicelli salt, mushroom salt, stalactite salt and pagoda salt in shape. Green salt can also be artificially shaped. Zhu De's inscription hanging screen and Tiananmen Square in Qinghai Hall of the Great Hall of the People are both carved with crystallized salt in green salt.