Abstract
In the Bazhenovskoye chrysotile–asbestos deposit (Middle Urals), nephrite bodies of the serpentinite type were found on the contact of after gabbro rodingites and serpentinites. The color is uniform to non-uniform, green to light green, bluish green, greyish green, and whitish. Spots, streaks, lenticules of bright bluish-green or, on the contrary, light green color are sometimes noted. The nephrite is mostly comprised of tremolite. Chromite decreases the quality of the ornamental stone, but it is replaced by chrome grossular, which gives the nephrite a brighter bluish-green color locally. Crushed grains of chromite contain increased concentrations of Zn and Mn. The quality of the nephrite is decreased by serpentine and talc, as well as by fractures due to drilling and blasting works. The specific feature of the nephrite in the Bazhenovskoye deposit is the formation of nickeline, maucherite, and uvarovite. The green color is associated with Fe2+ ions. The nephrite of the Bazhenovskoye deposit meets the requirements for an ornamental stone. The origin of this nephrite includes a combination of metasomatic and metamorphic processes.
Highlights
The nephrite block contacts gabbro through a transitional zone—A bright green opaque tremolite rock with inclusions of ore minerals—its thickness is 15 cm
The tasks were set to show that the nephrite of the Bazhenovskoye chrysotile–asbestos deposit (Middle Urals) meets the requirements for this ornamental stone, to study its specific mineral composition and the nature of its color, and to determine the features of its origin
Nephrite is composed mostly of tremolite; chromite decreases the quality of the ornamental stone, but it is replaced by chrome grossular, giving the nephrite a brighter green color
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Nephrite is a highly marketable piece of jewelry and ornamental stone that has long been used by humans, especially popular in China and some other countries. The most valuable nephrite is translucent white, black, and bluish green, with a minimum amount of ore minerals. Nephrite deposits belong to two endogenous geological–industrial types: serpentinite type (after serpentinite metasomatites at ophiolites) and dolomite type (after dolomite tremolite–calcite magnesian skarns). Deposits of the first type are a source of mainly greento-brown and black nephrite, deposits of the second type give mainly light-colored nephrite from white to green, brown and black in color. The exogenous geological–industrial type of placers, usually alluvial, is confined to the primary sources
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