Science / Geology / Mohs Hardness Scale: A collection of minerals ranging from very soft to very hard. Use as a comparison scale during mineral identification. From softest to hardest, the ten minerals are: talc 1, gypsum 2, calcite 3, fluorite 4, apatite 5, orthoclase 6, quartz 7, topaz 8, corundum 9, and diamond 10. Developed by Friedrich Mohs, a German mineralogist in the early 1800's.
Scale Noun Synonyms: coating, encrustation or incrustation, crust, overlay, layer, cake, caking, tartar, plaque
Scale Adverb Synonyms: flake, imbrication, scurf, dandruff, squama, plate, scute or scutum, lamina, lamella
Science / Chemistry / Permanent Hardness: Water hardness that remains after boiling the water, mainly due to dissolved calcium sulfate. Chlorides also contribute to permanent hardness. MORE
Entertainment / Music / Pentatonic Scale: Five-note pattern used in some African, Far Eastern and Native American musics: can also be found in Western music as an example of exoticism. MORE