Some soils, like the soil in this picture, contain a large number of coarse fragments. Any mineral particle greater than 2.0 mm in diameter is considered a "coarse fragment." In this picture, the soil contains many large rocks. Larger particles, like these rocks, have little moisture or nutrient holding capacity, so soil scientists pay attention to the quantity of coarse fragments in the mineral soil. Soils that contain more than 15% by volume of fragments greater than 2.0 mm in diameter are known as "skeletal." A soil with a high rock content not only has lower moisture and nutrient holding capacity, but it could also present equipment limitations. For example, it would be difficult to machine plant a soil with as many rocks as the one in this picture.