Mohs Hardness Scale

The Mohs scMohs scale of mineral hardness-GeologyPageale of mineral hardness is a qualitative ordinal scale that characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German geologist and mineralogist Friedrich Mohs and 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, however, is 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. 77 AD. While greatly facilitating the identification of
Source: Mohs Hardness Scale

A meditative moment

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Some days the chatter in the office gets a bit irritating. Yesterday it reached the point where I just couldn’t concentrate on what I was doing. So I got up and went outside. The edge out front between the sidewalk immediately in front of the office and the curb is filled with river stones. When I walked out I had intended to go to my car and just sit for my break and just reset from the cocktail party that was going on among my coworkers. When I’m around any group that is getting increasingly loud and chatty I have to do this sometimes. When I stepped out the rocks caught my eye and I decided to select five or six to build a miniature version of the rock balancing “cairn” sculptures. The display out front is mostly flat white-ish stones of the skipping variety. I bent down to pick one up and the security guard who was close by asked, “Is there something wrong with the rocks?” I looked at him and shook my head and went back to scanning the rocks. I spent the next fifteen minutes going over most of what’s there and the sense of agitation that I was feeling went away. I found these five that would work and I took them inside and placed them on my desk next to the Mac.