Scratch hardness Scratch hardness Scratch hardness tests are used to determine the hardness of a material to scratches and abrasion. The earliest test was developed by mineralogist Friedrich Mohs in 1820 (see Mohs scale). It is based on relative scratch hardness, with talc assigned a value of 1 and diamond assigned a value of 10. Mohs' scale had two limitations; it was not linear, and most modern abrasives fall between 9 and 10. Raymond R. Ridgway, a research engineer at the Norton Company, modified the Mohs scale by giving garnet a hardness of 10 and diamond a hardness of 15. Charles E.
101 George Street, The Rocks history of New South Wales. The place possesses a degree of rarity as the first site to be the subject of heritage renovations/reconstructions in the 1970s, when the plans of the Sydney Cove Redevelopment Authority to raze The Rocks for redevelopment were still in place. The place is important in demonstrating the principal characteristics of a class of cultural or natural places/environments in New South Wales. The scale and streetscape character of the Phillip's Foote building is representative of early 19th commercial building in The Rocks as a plain two-storey shop with residence. 101 George Street, The Rocks 101 George