Jade is a mineral.

There are two kinds of jade: soft and hard. Usually, jade refers to nephrite. It belongs to one of the most common jewels.

According to "Tengyue Local Records" written by Qing Jinshi Cun Kaitai, Tengyue collected jade works, made them into utensils and sold them to various provinces in Yunnan. Top grade jadeite is mostly sent to eastern Guangdong, Shanghai, Fujian, Zhejiang and Kyoto.

China is the earliest and most extensive country in the world to exploit and utilize jade. There are many records and names in ancient books, such as Shuiyu, Heritage Jade, Peiyu, Xiangyu, Nephrite and so on. Tremolite nephrite unearthed from Chahai site in Fuxin city, Liaoning province is about 8000 years ago (early Neolithic age), which is the earliest known real jade in the world.

The most famous jade in China is Hetian jade in Xinjiang, which, together with dushan jade in Henan, xiuyan jade in Liaoning and lantian jade in Shaanxi, is called the four famous jade in China.

Jade detailed introduction:

The quality of jadeite is generally judged from five aspects: texture, hardness, transparency, specific gravity and color. The texture of jade refers to the delicate and moist degree of jade. One of the differences between jade and stone is that jade is delicate, moist and hard, translucent and glossy as fat; Stone, on the other hand, is rough and dry, lacking luster and opaque.

Hardness refers to the ability of jade to resist external forces (such as pressing, engraving and grinding). The higher the hardness, the more difficult it is to process and the better the quality of jade. Although the hardness index of jade can be known by detecting its internal crystal structure with instruments, the method of scraping hardness is generally used in operation.

The hardness of common jade in China is between 4 and 6 degrees, which is higher than copper and lower than glass. In other words, jade may not be able to carve marks on glass.