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.
Orient Hotel, The Rocks of The Rocks under SCRA erupted in 1973 in organised community protests supported by the NSW Branch of the Builders Labourers' Federation. By 1975, SCRA's planning outlook had evolved to take into consideration cultural, social and historical values, but large scale developments continued. The Orient Hotel with its corner location and historic street presentation has contributed to the public's association of The Rocks with a unique historic neighbourhood. Around 1976, a company named Rocks Hotels Pty Ltd. took on the management of the hotel and in 1979 extensive alterations valued at $120,000 were completed to provide street facades approximating its