Each stone is unique and may differ slightly in size, shape, color and pattern from the picture.
Obsidian is caused by rapid cooling of lava with a maximum water content of 4 percent. At higher contents of volatile substances (besides water mainly CO2), otherwise the rock would puff up to a pumice even on rapid cooling. Slow cooling causes Pechstein.
Note: The effect of gemstones, minerals and crystals has not been scientifically recognized. All statements on this page are not intended to be diagnostic or therapeutic.