Obsidian 曜石

Obsidian is a naturally occurring volcanic glass that forms when molten lava cools quickly. Obsidian is a common black gemstone, also known as "Dragon Crystal or "Tokachi Stone". It is a naturally occurring silica that is usually black in color. Obsidian is one of the Seven Treasures of Buddhism.

The most common colors of Obsidian stones are black. However, Obsidian can also be found in greens, tans, and browns. Rare colors of Obsidian can be found in blues, reds, yellows, and oranges, and even two colors in a swirled-together, marble-like pattern. 

Often used in Feng Shui, Obsidian is considered a protector of the home and workplace and a dispeller of negative energy.