Mohs scale of mineral hardness Mohs scale of mineral hardness The Mohs scale of mineral hardness is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. Created in 1812 by German geologist and mineralogist Friedrich Mohs, it is one of several definitions of hardness in materials science, some of which are more quantitative. The method of comparing hardness by seeing which minerals can visibly scratch others is, however, of great antiquity, having been mentioned by Theophrastus in his treatise "On Stones", c. 300 BC, followed by Pliny the Elder in his "Naturalis Historia", c.
The Rocks Crumble 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 gently, and its approach echoes the cover, in which an old Slingerland drum set