Sand – friable sedimentary rock, as well as artificial material, consisting of grains of rocks. Very often consists of an almost pure quartz mineral (the substance is silica). The word “sand” is often used in the plural (“sand”), but the plural form has other meanings. Natural sand is a loose mixture of grains formed as a result of the destruction of solid rocks, 0.16–5 mm in size, the mass of one grain of sand can vary from tenths of a milligram to several micrograms. Depending on the conditions of accumulation, they can be alluvial, deluvial, marine, lake, eolian. Sands resulting from the activity of water bodies and watercourses have a more rounded, rounded shape.
