What is the "mica" in Li Shangyin's poem? Electric irons and electric ovens cannot do without it

"The candlelight is deep behind the mica screen, the morning stars are sinking as the long river gradually falls. Chang'e should regret stealing the elixir, as her heart is filled with the blue sky and the blue sea every night." This is a poem about Chang'e written by the "unpopular poet" Li Shangyin. The poem uses the recollection of Chang'e and the moonlight shining through the mica screen to make the room with the faint candlelight appear even more desolate and deep, expressing the poet's lonely mood.

Li Shangyin, Late Tang Dynasty, "Chang'e" (Picture from the Internet, please delete if infringed)

Mica screen is a screen made of inlaid mica sheets. In the poet's time, it was a popular collectible that even unpopular poets would buy, because it has a very good temperament: between transparency and opacity, it contains a looming sense of mystery; the pattern is beautiful and elegant, showing an extraordinary aesthetic taste; it is expensive, and is a symbol of status.

Mica screen (picture from the Internet, please delete if infringed)

Mica is a type of silicate mainly containing aluminum and potassium. It is classified as the mica family in the mineral category, including a series of minerals with similar chemical composition and the same crystal structure type, such as muscovite, phlogopite, sericite, etc.

The temperament of mica screens comes from the nature of mica itself: mica crystals are rhombus-shaped plates, scales, etc., with smooth surfaces and complete cleavage. They are easy to peel off layer by layer, and they are as elegant as clouds. The peeled layers of thin sheets are transparent with slight yellow, brown, green and other tones, so they look hazy and mysterious.

The layered structure of muscovite crystals in the museum collection

In addition, Ge Hong, Tao Hongjing and other pharmacists and alchemists endorsed its miraculous effects. For example, Baopuzi said, "(Take it) for one year, all diseases will be cured, take it for three years, an old man will turn into a boy, and Wei Shuqing of Zhongshan took it for a long time, and he could ride on clouds." Later, alchemists at that time were obsessed with foreign goods, and they would never use local products if they could get imported raw materials brought by Western merchants. Whether you can really ride on clouds after taking it is not to mention whether you can really ride on clouds after taking it, but the price is sky-high.

Picture of Ge Hong making elixir ** (Picture from the Internet, please delete if infringed)**

In fact, as one of the main rock-forming minerals with widespread distribution, mica is not uncommon and is found in igneous rocks, sedimentary rocks and metamorphic rocks. For example, an ordinary granite (which belongs to the igneous rock type) contains three common rock-forming minerals: mica, quartz and feldspar.

Granite specimens in the collection

The museum's collection of mica and aquamarine symbiosis specimens

The museum's collection of mica and tourmaline symbiotic specimens

Mica can not only be used as a decoration, but also has a good heat insulation effect. This property has long been discovered and used by the ancients. For example, incense was very popular in the aristocratic and literati circles in ancient my country. As a high-end way of health preservation and cultural activities, it has also formed an incense culture, which is very particular. In addition to selecting the types of spices, it is also required that the incense should not be as good as the fire, so that there is no smoke and fire, but there is a natural fragrance. The method is to use a shallow plate made of mica sheets to hold the incense, which is called fire-separated incense. Fire-separated incense requires that the incense should not be smoked, and the taste is clear and deep. It is the highest way of hospitality for scholars and officials when facing distinguished guests. The host will take out the collection of incense materials, invite two or three incense friends, put a layer of mica sheets on the charcoal, put the incense on the mica sheets and slowly fry and roast them, order tea and have a chat during the time, and finally end with the literature and calligraphy left on the incense seals and incense books.

Mica sheets are used to hold spices and burn incense over fire (Picture from the Internet, please delete if infringed)

In modern times, mica is also used as an insulating material in our lives. Electric irons, electric ovens, etc. all use mica as insulating materials. In addition, its scaly structure can fill the pits and bumps on our skin, which is not smooth at a microscopic perspective, so that light forms a mirror reflection. It is non-toxic and non-irritating, so it can also be used in cosmetics to make the skin look whiter and more shiny.

Cosmetics based on mica ** (Picture from the Internet, please delete if infringed)**