What is orpiment?

Orpiment is a sulfide mineral containing arsenic, and its chemical formula is As2S3. It has bright yellow or orange, can be used to make arsenic and arsenic compounds, and is also an ancient painting pigment and Chinese medicine.

Crystal structure and properties of 1. orpiment

Orpiment belongs to monoclinic crystal system, and its crystals are often tabular or short columnar, and its aggregates are flaky, comb-like and earthy. Orpiment has a layered structure, along which perfect cleavage occurs, and the cleavage surface is pearly luster. Orpiment hardness 1.5-2, relative density 3.49, refractive index 2.4-3.02 and birefringence 0.62.

Second, the cause and origin of orpiment

Orpiment is mainly formed in low-temperature epithermal deposits, which is generated by the reaction between arsenic-containing sulfide and hydrogen sulfide. Orpiment can also be formed around volcanoes and hot springs, which is the product of volcanic sublimation or hot spring deposition. Orpiment is often associated with another arsenic-bearing sulfide mineral realgar, which is inseparable.

The associated minerals of orpiment are stibnite, white iron ore, pyrite, cinnabar, calcite and gypsum. Orpiment is distributed all over the world and produced in China, Hunan, Yunnan, Guizhou, Sichuan, Gansu and other provinces.

Modern use and scientific value of orpiment

In modern times, orpiment is mainly used to make arsenic and arsenic compounds. Arsenic is a nonmetal, which plays an important role in semiconductor industry and leather industry. Orpiment can also be used to produce infrared transparent glass, linoleum, linoleum, photoconductor, pigment and fireworks.

Orpiment is also a kind of crystal material with scientific value. There are many interesting phenomena in its optical properties and electronic structure, such as photochromic, photoinduced phase transition, electro-induced phase transition and so on. It is an ideal model for studying low-dimensional physics and solid chemistry.

Historical use and cultural significance of orpiment

1, historical use

In ancient China, orpiment was also a traditional Chinese medicine, which was used to kill insects, detoxify and reduce swelling, but it was very toxic and was no longer used in modern medicine.

2. Cultural significance

Orpiment is a material with a long history. As early as ancient Egypt, it was used as a painting pigment and wax. Because of its striking color, it attracted the interest of China and western alchemists in order to find a way to make gold. Orpiment was found on the wall decoration of Tutankhamun's tomb, the scrolls of ancient Egypt and the walls of the Taj Mahal.