One Volcano can have many different lava flows, with different hardness, color, and rock type, because of the maximum temperature the flow reaches and how it's cooled. The Black Lava Rock we carry is called cinder, or foamed obsidian. Obsidian sometimes called flint is very hard, and is what arrow heads were made of by native American Indians. There is a big difference between obsidian and foamed obsidian. Foamed Obsidian occurs when gases in the magma did not escape because of rapid cooling.

Volcanic Lava Rock is very porous and weighs less than half that of other landscape materials making it easy to transport and spread. Lava Rock insulates the soil from heat and cold. Studies show that lava rock is more effective in retaining moisture in topsoil, than wood mulch products. It helps better regulate moisture in the ground and will not rot, decay or be subject to color fade like wood mulches, making it a permanent mulch replacement.