One of December mascot stones is considered to be obsidian, a mineral formed as a result of rapid cooling of molten lava.  The process of cooling and solidification takes place in a very short time, which is insufficient for crystal growth. Consequently, the mineral cannot be assigned to any crystal system. It is an amorphous natural volcanic glass composed of silica. The silica content is 66-75%.  During the process of lava solidification, air bubbles may be trapped in it, which remain in the mineral after it has cooled down completely. It is the bubbles that give this mineral such effects as luminescence and iridescent sparkle. The stone got its name in the times of ancient Rome. A warrior named Obsius (some versions say Obsidian) brought the shiny black stones to the capital from Ethiopia, which have been named in his honour ever since. According to another version, the name comes from the word "obsis", which means "spectacle" in Greek. The name may have originated from the fact that in ancient times obsidian was used to make mirrors.

Obsidian was used to make arrowheads, knives and scrapers. The ancient Maya piercing-cutting weapon from it. Also archeologists have found surgical instruments – obsidian splits in such a way that the sharpness of the corners can reach the level of laser sharpening.

Obsidian belongs to the category of semi-precious decorative stones. It is divided into types depending on its colouring. The magnesium and iron oxides in the stone affect its colour. Usually it is coloured black, but may have patterned blotchiness. In terms of colour, the stones are found in nature in the shades ranging from dark brown to deep black. Obsidians belong to the category of quite rare stones, since they are found only in the areas of ancient volcanoes or where there were campsites of primitive people. The Russian Federation (Karelia and Kamchatka), Japan, China, India, Ecuador, USA are rich in similar discoveries.

Obsidian has the same wide range of uses now as it did thousands of years ago. Obsidian is used extensively in both decorative and jewellery pieces. Decorative objects can be carved entirely from obsidian, while its faceted shards are used in jewellery as inserts. Obsidian continues to play an important role in surgery. Volcanic glass can be used for a cutting edge that is thinner and sharper than the best surgical steel. Thin plates of obsidian are placed in surgical scalpels used for some operations. The stone is also in demand in manufacturing of various insulating materials.

Ancient people believed that obsidian was sent to them by higher powers. Therefore, it was always associated with something sacred, energetically powerful and symbolic.  Greek mythology tells us that obsidian emerged from the claws of Cerberus (Kerber), the three-headed dog that guarded the gates of Hades, the place where the souls of the dead descended. Thus, obsidian came to be regarded as a mineral linking to the gods and reflecting their energy.  In the Transcaucasia countries, this stone has long been known by the gloomy name "satani ekhunk" ("devil's claw"). People believed that obsidian was from the claws of his sable Excellence, broken when he fell from heaven into the depths of hell. Obsidian (volcanic glass) is used by sages, clairvoyants and extrasensory perception adepts. In their practices obsidian broadens the horizon and helps to get rid of narrow-mindedness and tunnel vision. A person begins to bear adversities easily and becomes more optimistic. Medieval sorcerers used smooth obsidian balls to divine the future. And Indian yogis even nowadays purify their souls from dark feelings with this mineral and perform rituals to strengthen the body, after which, as eyewitnesses say, a person feels as if reborn.

Obsidian prayer beads sharpen the abilities of clairvoyants, enhance intuition, and increase magical power. And obsidian glass, carved in the form of a small shield, can create a barrier, stopping the attempts of uninvited spirits to enter our world. Obsidian is sometimes called the "stone of truth" because it helps to reveal secrets and hidden emotions. The mineral gives protection from negative energy, it is ideal for December Capricorns. It helps them to strengthen their character.

In lithotherapy it is believed that obsidian is good for those who have problems with liver or dreams of getting rid of excess weight, that is, for cleansing the body. It is also said that obsidian stone helps to fight insomnia and improves the quality of sleep. The stone stimulates people who lack initiative, energises them and makes them want to change their lives.

Items made from obsidian or with its fragments are in the "Lapidary works of Art" section of the museum Collection:

On the cover: "Bear meets Queen Bee" jewelry set. Luis Alberto Quispe Aparicio, Brazil. 2019

Panda Bear Fountain Pen. Luis Alberto Quispe Aparicio, Brazil. 2019
Carved figurine of a beaver in the Fabergé style. Russia. The 20^th century
Carved figurine of a rooster in the Faberge style. The 20^th century
Steer. Erwin Klein. Germany, Idar-Obershtain. 1985
Three wise monkeys. Schmitt Christoph. Germany, Idar-Oberstein. The 20^th century
Vintage roller-skate. Luis Alberto Quispe Aparicio, Brazil. The 20^th century
Duck. Manfred Wild. Germany, Idar-Oberstein. The 20^th century
Carving of big horn sheep. Germany, Idar-Oberstein. The 20^th century~
Bear. Early 20^th century
Gorilla. Luis Alberto Quispe Aparicio, Brazil. The 20^th century
Horse's head. Luis Alberto Quispe Aparicio, Brazil. The 20^th century
Fledgling crow. Manfred Wild. Germany, Idar-Oberstein. The 20^th century
Hippopotamus. Germany, Idar-Oberstein
White-tailed sea eagle. Graveur Atelier Reiner Stein. Germany, Idar-Oberstein. The 20th century

Ref.:
https://www.livemaster.ru/topic/2364057-tainstvennyj-obsidian-zagadochnoe-ocharovanie-chernogo-tsvet....
https://dzen.ru/a/XcbVj3fBYXrK0GU_
http://paranormal-news.ru/news/obsidian_tajny_kamennogo_stekla/2018-03-15-14466
https://info.gemworld.store/obsidian/