Rhyolite Granite is a fine-grained igneous rock (magmatic) mined from the Arbuckle Mountains. It is considered the extrusive equivalent (formed above ground) to the intrusive (formed below ground) granite rock and consequently bears a resemblance. This volcanic stone is dark gray, near black when wet. The rock was used to make arrowheads and spear points but is commonly used as a low dust cover on driveways and walking paths today. Ideal for patios and firepits. Screened to 3/8” stones and chat mix creating a firm and stable base.