Gold panning is a form of mining that extracts gold from a placer deposit using a pan. The process is one of the simplest ways to extract gold, and is popular with geology enthusiasts because of its cheap cost and the relatively simple and easy process involved. Pans are measured by their diameter in inches. Common sizes of gold pans today ranges between 10-17 inches, with 14 inches being the most used size. Pans are manufactured in both metal and high impact plastic. Heavy gauge steel pans are traditional. Steel pans are heavier and stronger than plastic pans. Some are made of lightweight alloys for structural stability. Plastic gold pans resist rust, acid and corrosion, and most are designed with moulded riffles along one side of the pan. Of the plastic gold pans, green and blue ones are usually preferred among prospectors, as both the gold and the black sand stands out in the bottom of the pan.