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.
Lilyvale, The Rocks is an integral component of a group of 19th century houses in this section of Cumberland Street, which evokes a traditional Rocks streetscape. "Lilyvale" (176 Cumberland Street), the Butchery Building (178-180 Cumberland Street) & Hart's Building (10-14 Essex Street) as a group: The surviving buildings occupying the block bounded by Cumberland, Essex and Gloucester Streets, south of the Cahill Expressway, collectively illustrate the range and diversity of small scale development in this area of The Rocks between 1840 and World War I. They combine with nearby precincts to the south of Essex Street to extend that diversity into the early