10 Different Types of Gravel (w/ Pictures
#0183;#32;They may have round or sharp edges, be smooth or rough, and may be natural or manmade. Stones smaller than 3/16 inches are classified as sands, while those over 3 inches are called rocks. Note: The terms rock and sand may sometimes be used interchangeably with gravel in relation to the size or a specific type of stone material. Types of Gravel 1.