sexta-feira, 15 de agosto de 2014



The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German geologist and mineralogist Friedrich Mohs (1) and is one of several definitions of hardness in material science, some of which are more quantitative. The method of comparing hardness by seeing which minerals can visibly scratch others, however, is of great antiquity, having been mentioned by Theophrastus in his treatise De lapidibus (On Stones), c. 300 BC, followed by Pliny the Elder in his Naturalis Historia, c. 77 AD.
While greatly facilitating the identification of minerals in the field, the Mohs scale is not suitable for accurately gauging the hardness of industrial materials.

Friedrich Mohs (1773 - 1839) geólogo e mineralogista alemão.

Teofrasto (Θεόφραστος nasceu em Eresos, 372 a.C. Athená  287 a.C.) filósofo, sucessor de Aristóteles no Liceu.
(Θεόφραστος = Theophrastus: Θεό = divino, deus + φράσ-τησ, ου, ὁ, = Lat. Eloqüente. 
sucessor de Aristóteles na escola peripatética. Era oriundo de Eressos, em Lesbos, seu nome original era Tirtamo, mas ficou conhecido pela alcunha de 'Teofrasto', que lhe foi dada por Aristóteles, segundo se diz, para indicar as qualidades de orador.

             FRIEDRICH MOHS 


Hardness scale pic: from internet
Text from: The Wikipedia (modificado) 

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