Amber: Amber that sinks into the earth is the spirit that freezes time.

The protagonist of this issue is an organic mineral - amber, which is a perennial favorite in the field of art and collection. The well-known beeswax is a type of amber. The amber specimen on the cover of this issue comes from the Gdansk region on the Baltic Sea coast, which is one of the world's famous amber producing areas.

The English name of amber, "Amber", comes from the Latin word Ambrum, which means "essence". There are also claims that it comes from the Arabic word "Anbar", which means "glue". Amber is a natural petrified organic matter formed by the liquid resin produced by coniferous plants in the geological period (most of which are within 100 million years ago) after various geological processes. It is also called "resin fossil" or "rosin fossil". The origin of the name "amber" in my country is that in ancient times, when a tiger died, people believed that its spirit immediately went underground and turned into stone, so it was called "tiger soul", and later changed to "amber". In my country, the emergence of the word "amber" can be traced back to the Western Han Dynasty more than 2,000 years ago. In Lu Jia's "New Language·Daoji Chapter", it was recorded that "amber coral, emerald feathers, pearls and jade, mountains and waters, choose the right place to live...". The Tang Dynasty poet Wei Yingwu once wrote in the five-character quatrain "Ode to Amber": "Once an old Fu Shen, originally cold pine liquid. Mosquitoes and gnats fell into it, and they can still be seen after a thousand years."

Amber from Gdansk on the Baltic coast (one of the world's largest rock mineral specimens)

The chemical composition of amber is relatively complex. It is mainly composed of soluble oligomer small molecules and polymers that are difficult to dissolve in organic solvents. It is a typical multi-component organic mixture that is not easy to decompose.

In terms of physical properties, amber is light yellow to honey yellow, yellow-brown to brown, light reddish brown, light red, light green brown, white, blue, light green, lavender, etc. It is an amorphous body with a low Mohs hardness (2-2.5) and can be scratched with a knife or even a fingernail; it has a resin luster and a refractive index of 1.540; the relative density is very low at 1.08 (+0.02, -0.08), and it is the lightest variety of known gemstones. It can be suspended in saturated concentrated salt water. The amber we usually see in nature has a variety of irregular shapes due to wear and tear during the transportation process of geological actions, and has traces of broken and opaque skin. After processing and polishing, amber can present different luster and colors. Its transparency is like crystal, and its color is like agate. Among them, the opaque ones with honey color and wax light are also called "beeswax".

Insect amber specimen (collected by Kunming Museum of Geology)

Amber containing impurity inclusions is called impurity amber, among which the inclusions of various insects are called insect amber; the inclusions of plant organs such as branches, leaves, roots, stems, seeds, etc. related to plants are called plant amber (flower amber); the inclusions of flowing water bubbles are called water gall amber, which has certain scientific research and ornamental value. When amber contains various organisms that lived in the same geological period, it is given a new meaning and becomes a "time capsule" of the evolution of life on Earth. Because the animals and plants preserved in it often have very rich detailed characteristics, they are extremely precious "memory fragments" and are of great significance to the study of life evolution.

In addition, amber has significant value in commerce and medicine. Since the Neolithic Age, the beauty of amber has been highly praised, and various ornaments made of amber are also one of the most sought-after gemstones. As an organic gemstone, beeswax has various forms and is all-encompassing, and has a large number of collectors at home and abroad. Amber can also be used as medicine, which has the effects of calming the nerves, relieving shock, and promoting blood circulation and diuresis.

Insect amber specimen (collected by Kunming Museum of Geology)

Many countries around the Baltic Sea, such as Denmark, Poland, Russia, and Ukraine, are the world's most important and concentrated amber production areas. In addition to the Baltic Sea coast, Dominican Republic, Myanmar, Mexico, China and other places are also important amber production areas. Among them, Dominican Republic is famous for producing "blue amber" with a blue-green fluorescent surface. my country's amber is mainly produced in Liaoning, Henan, Guangxi, Guizhou, Yunnan, Zhejiang, Chun'an Qiandao Lake, and Jilin Hunchun.

Appendix: This issue of amber from Gdansk on the Baltic coast belongs to the world's rock and mineral specimens, which are treasured in the Earth Science Museum of Kunming University of Science and Technology. It is one of the geological teaching specimens customized through the "Boxer Indemnity" in the early years of the Republic of China. Many specimens were collected from the original naming places of rocks and minerals, classic mining areas and stratigraphic sections. Some mineral deposits no longer exist after long-term mining, so many collected specimens cannot be recovered. This set of specimens moved south during the Anti-Japanese War, and after several twists and turns, it was preserved in Kunming University of Science and Technology through the National Southwest Associated University. It has been preserved almost intact to this day, witnessing the formation and development of China's modern geological disciplines and earth science education, and has important scientific research, historical and cultural relic value.

Written by: Zhu Jun, Gao Danxia, ​​Shen Cen, Wang Lei

Scientific Advisor: Zhang Shitao

Photographed by: Yang Yuchen

Supporting institution: College of Land and Resources Engineering, Kunming University of Science and Technology