Mohs, Friedrich

Christian Samuel Weiss (1780-1856) and Friedrich Karl Mohs (1773-1839) derive the six different crystal form classes cubic, orthorhombic, rhomboidal, hexagonal, monoclinic, and triclinic. 

A mineral s hardness is defined as its ability to scratch another mineral. This is usually measured using a comparative scale devised about 200 years ago by Friedrich Mohs. The Mohs scale lists ten common minerals, assigning to each a hardness from 1 (talc) to 10 (diamond). A mineral can scratch all those minerals having a lower Mohs hardness number. For example, calcite (hardness three) can scratch gypsum (hardness two) and talc (hardness one), but it cannot scratch fluorite (hardness four). 

Which has the greater hardness—cuprite (CuaO) or chalcocite (CuaS) Hardness is the relative resistance to abrasion and is measured on a scale devised by the German mineralogist, Friedrich Mohs, in 1812. On this scale, various... 

Substances, mostly minerals, are ranked by their ability to scratch one another. If one mineral can scratch another mineral it gets a higher ranking on the Mohs hardness scale. When Friedrich Mohs devised the scale, diamond was the hardness substance known, so it was given a value of 10. Talc (also known as talcum powder), being very soft, has a hardest rating of only 1. Mohs devised this scale to help sort out the private rock collection of an Austrian banker, and later the Archduke s museum collection. There are more quantitatively accurate measurements of hardness available today, but the simplicity of the Mohs scale keeps it relevant and practical. 

Mohs scale A hardness scale in which a series of ten minerals are arranged in order, each mineral listed being scratched by and therefore softer than those below it. The minerals are (1) talc (2) gypsum (3) calcite (4) fluorite (5) apatite (6) orthoclase (7) quartz (8) topaz (9) corundum (10) diamond. As a rough guide a mineral with a value up to 2.5 on this scale can be scratched by a fingernail, up to 4 can be scratched by a coin, and up to 6 by a knife. The scale was devised by Friedrich Mohs (1773-1839). 

Berzelius s second arrangement was used by Friedrich Mohs (Gemrode, Harz, 29 January 1773-Agordo, Tyrol, 29 September 1839), Wemer s successor in Freiberg (1818) and later professor in Vienna (1826-35), and by his successor in Freiberg... 

Mohs scale [Friedrich Mohs f 1839 German mineralogist[ (1879) n. Scale for... 

Staples, L.F. Friedrich Mohs and the scale of Hardness J. Geol. Education, 12 (1964) 98-101. 

The s)Tstematic classification of minerals according to the American Chemist and Mineralogist James Dwight Dana was the first to be established in 1837 using the Linnaen principles of taxonomy modified by Friedrich Mohs and the Berzelius system for the notation of chemical formulae. Since 1837, it was modernized to take into account recent discoveries. 

In 1822, Friedrich Mohs developed a hardness scale for minerals, using ten minerals. From hardest to softest, they are diamond, corundum, topaz, quartz, potassium feldspar, apatite, fluorite, calcite, gypsum, and talc. 

German metallurgist Friedrich Mohs proposes the Mohs scale for mineral hardness. 

Mohs scale Friedrich Mohs (Germany) proposes a scale of mineral hardness. [1822]... 

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