to opaque and have Human Hair Extensions a Mohs hardness of 7.Obsidian is natural volcanic glass that forms as lava cools and can take various forms and colors, depending on the composition of the lava. For example, Wigs "mahogany obsidian" has reddish-brown streaks running through it and "gold sheen", as the name suggests, has a golden, glittery sheen. In its pure form Brazilian hair obsidian has a dark body color.