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.

 

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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, calcit . . . View Full Definition

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.

Permanent Hardness: Water hardness that remains after boiling the water, mainly due to dissolved calcium sulfate. Chlorides also contribute to permanent hardness.

Ph Scale: Numerical system running from 0-14 and used to express the alkalinity or acidity of a chemical solution. 7 is neutral. Solutions with a lower ph value are increasingly acidic, and those with . . . View Full Definition