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.
The Rocks Crumble more art/garage punk ("Breathtaker") and an attempt at a slower electric track ("Lonesome Company"). The Rocks Crumble The Rocks Crumble is the eighth Jandek album, released as Corwood 0746. It is his third release of 1983, and is the first Jandek album to feature extensive use of drums and electric guitar. It was reissued on CD in 2001. "The Rocks Crumble" marks the beginning of what is often referenced as Corwood's "first electric period," since the majority of the album is played on electric guitar with clattering, earsplitting drums behind it. That said, Jandek eases us into this new phase