Human: I've heard that there are many different types of sand. What are they? Assistant: 
Sand can be classified into two categories, based on its size and mineral composition: silt and sand. Silt is finer than sand, with a grain size ranging from 0.05 mm to 0.002 mm, while sand has larger grains between 0.002 mm and 2 mm in diameter. Silts are composed of clay minerals and organic matter, whereas sands are made up of quartz and feldspar minerals.