ragÂ·top (rÄgâ²tÅpâ²) n. Slang A convertible automobile. ragtop (ËrÃ¦É¡ËtÉp) n 1. (Automotive Engineering) a. a vehicle roof made of fabric, which can be folded back or removed b. (as modifier): a ragtop roadster. 2. (Automotive Engineering) (as modifier): a ragtop roadster. 3. (Automotive Engineering) a vehicle with a ragtop.
Mohs scale of mineral hardness. The mohs scale, named after Friedrich Mohs. Mohs scale of mineral hardness is named after the scientist, Friedrich Mohs, who invented a scale of hardness based on the ability of one mineral to scratch another. Rocks are made up of one or more minerals. According to the scale, Talc is the softest: it can be scratched by all other materials. Gypsum is harder: it can scratch talc but not calcite, which is even harder. The hardness of a mineral is mainly controlled by the strength of the bonding between the atoms and partly by the size of the atoms. It is a measure of the resistance of the mineral to scratching. The Mohs scale is for natural minerals. For manufactured products other measures of hardness are better.
See Hardnesses of the elements (data page) Numbers in parentheses below are the Mohs Hardness. Mercury, of course, is a liquid. Very soft. The Group I metals are soft enough to dent with your fingernail: cesium (0.2), rubidium (0.3), potassium (0.4), sodium (0.5), lithium (0.6). Some of the Group II metals are pretty soft: barium (1.0), calcium (1.5). Other common soft-ish metals: Lead (1.5), tin (1.5), cadmium (2.0), gold (2.5), silver (2.5)