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.
Gemstone Hardness. The Mohs scale of mineral hardness was created by German mineralogist, Friedrich Mohs, in 1822 to measure the relative hardness or scratch resistance of various minerals. He based it on ten readily available minerals. As it is an ordinal scale, two minerals must be compared to decide which is harder. The scale is neither linear nor logarithmic.