The Mohs hardness scale below was devised when the hardest or most resistant known mineral or gemstone was the diamond. The minerals, below in the Mohs scale are classified by number 1 to 10 of hardness. When a mineral can be scratched by another mineral of greater hardness this is classified by the Mohs number. If a piece of quartz was to scratch an Orthoclase feldspar the Orthoclase feldspar is classified as 5 to 6 of hardness on the Mohs scale. The actual hardness of these minerals can be 4 or more times and this is classified in the absolute hardness number. Gypsum being three times hardness of Talc, Apatite forty seven times the hardness of Talc and so on.