The identification of fragmental-textured rocks can be quite complex. We have reduced the complexity for you, there is only one! Fragmental rocks get their name because they have rock fragments embedded in them . Do you see any, they should be obvious? The matrix material is usually volcanic ash that can feel gritty and sometimes contains small shards of glass. The rock can be light in weight. If your sample does not match this description, Go Back to the previous step.