Obsidian is a natural volcanic basalt glass and a unique and precious material. It was formed when the volcano erupted. This glassy rock was formed when the high-temperature magma cooled and solidified rapidly. Obsidian has become one of the widely used materials in ancient and modern human society because of its unique appearance and diverse uses.

The main component of obsidian is silicon dioxide (SiO2), and its content is usually above 70%. It also contains many trace elements, such as iron, magnesium, calcium, sodium and potassium. These trace elements form colorful stripes and patterns in obsidian, which increases its decorative value.

Distribution of biotite origin

Obsidian is mostly distributed in areas with volcanic activity, such as Hawaii, Japan, Java Island in Indonesia, Iceland, Hungary, Lipari Islands in Italy, the former Soviet Union, Mexico, Ecuador, Guatemala and other places.

Dark black and monocular obsidian are distributed in Arizona and New Mexico. Indians call it "the tears of Apache". Most obsidian jewelry is produced in Central America and North America and is the national stone of the United Mexican States.

In the process of formation, because the temperature around the lava flow drops rapidly and the cooling rate is the fastest, the magma containing silicon dioxide quickly condenses into blocks. Obsidian usually appears around lava flows or near the seaside at the foot of volcanoes. Because of its unique formation process, the crystal of obsidian also contains 1%-2% water.