Mineral Tables for the Determination of Minerals by Their Physical Properties (Classic Reprint)

Angebote / Angebote:

Excerpt from Mineral Tables for the Determination of Minerals by Their Physical PropertiesStreak. - The streak of a mineral is the color of its fine powder. It is best obtained by rubbing the Specimen upon the streak-plate until a definite color is produced.Hardness - By hardness is meant the resistance that a mineral offers to abrasion or scratching. The relative hardness of a mineral is usually determined by scratching it successively by minerals or sub stances of known hardness, two minerals of the same hardness mutually scratching each other. The scale of hardness in common use, called the Moh's scale, in ascending degree of hardness, is as follows: 1. Talc, 2, Gypsum, 3, Calcite, 4, Fluorite, 5, Apatite, 6, Feldspar, 7, Quartz, 8, Topaz, 9, Corundum, 10, Diamond.The thumb-nail will scratch minerals up to 25 and the ordinary knife-blade up to 55 in the scale, with a little practice the relative hardness of a mineral under 6 can be approximately determined with a knife-blade. Above 6 the scale of hardness is necessary} The relative hardness of many of the 'metallic or submetallic minerals can Often be judged by the ease or difficulty in obtaining a streak on the streak-plate. Fine fibrous and fine granular minerals usually appear to be much softer than the individual fiber or grain would be, if it were coarser. Also the surface of some minerals is often much softer than the fresh interior, owing to alteration.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.