Mohs scale of mineral hardness incorporates additional substances that may fall between levels: Comparison between hardness (Mohs) and hardness (Vickers): 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
Measuring the Universe Measuring the Universe Measuring the Universe is a performance art work by Slovak artist Roman Ondak first installed in the Pinakothek der Moderne in Munich in 2007. The exhibition stars as a blank white wall and begins to fill when museum guards mark visitors' height along with their name and the current date. It is in the collection of Tate Modern in London, Pinakother der Moderne in Munich and MoMa in New York. The only items required for the installation were a white room and a few black markers. What began as a clean white space has been filled with