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.
95-99 George Street, The Rocks aesthetically significant for containing some of the most intact Victorian period interiors for shops and residences in The Rocks area, including internal linings, joinery, some door and window furniture and an original plan form. 95-99 George Street makes an important contribution to the streetscape of George St, and is of significance in continuing the uniform character of the small scale retail shop buildings found in The Rocks. The building is aesthetically significant for its contribution to the streetscape of Greenway Lane, one of the pedestrian laneways in The Rocks area which are highly significant as evocation of the colonial townscape.