Watch this incredible moment the dazzling interior of an obsidian rock is revealed after it is cracked open.

The filmer in Sacramento, California holds a filthy rock in their hand and taps the side of it with another rock following up with a much harder smack.

A visible crack occurs down the side of the rock when the filmer takes hold of both halves.

The rock is then slowly opened out to reveal the bright night-black obsidian inside. The difference of this rock's stunning interior compared to its dusty exterior is so stark it shocks the viewer.

My friend and I collected some obsidian and brought it home. I wanted to show the world what each dull-looking piece had inside, so I broke a piece off. This video was shot by my iPhone in my backyard. My dad is the one filming.