This is a mixed box of high grade spalls that includes, black obsidian, dacite and mahogany obsidian. This box is a nice mix of volcanic glass. All these materials have a great reputation for work-ability and makes it a great choice for the indecisive knapper that can't choose just one! Your purchase will contain 10lbs of premium (Grade-A) spalls that range from 4-7 inches long and are a great choice for the beginner to expert knapper. Stone shown in the picture is an example of what to expect. Actual pieces may very. Skill Range: Beginner to Expert.