Naturally occurring Cr(VI) has recently been reported in ground and surface waters. Rock strata rich in Cr(III)-bearing minerals, in particular chromite, are universally found in these areas that occur near convergent plate margins. Here we report experiments demonstrating accelerated dissolution of chromite and subsequent oxidation of Cr(III) to aqueous Cr(VI) in the presence of birnessite, a ...

An electron microprobe study has been carried out on platinum-group minerals, accessory phases, and chromite in several chromite deposits of the Alapaevsk ophiolite (Central Urals, Russia) namely the Bakanov Kluch, Kurmanovskoe, Lesnoe, 3-d Podyony Rudnik, Bol’shaya Kruglyshka, and Krest deposits. These deposits occur in partially to totally serpentinized peridotites. The microprobe data shows ...

In the Bazhenovskoye chrysotile–asbestos deposit (Middle Urals), nephrite bodies of serpentinite type were found on contact after gabbro rodingites and serpentinites. The color is uniform to non-uniform, green light green, bluish greyish whitish. Spots, streaks, lenticules bright bluish-green or, contrary, are sometimes noted. mostly comprised tremolite. Chromite decreases quality ornamental st...

Hydrocarbons such as CH4 are known to be formed through the Fischer-Tropsch or Sabatier type reactions in hydrothermal systems usually at temperatures above 100°C. Weathering of olivine is sometimes suggested to account for abiotic formation of CH4 through its redox lowering and water splitting properties. Knowledge about the CH4 and H2 formation processes at low temperatures is important for t...

Introduction: More than 80 L-chondritic fossil meteorites were found in Middle Ordovician limestone in the Thorsberg quarry at Kinnekulle in southern Sweden [1, 2]. All meteorite-bearing sediment beds at Thorsberg contain sediment-dispersed extraterrestrial chromite (SEC) grains of L chondrite composition [3]. Similar SEC grains were also found in several correlated sediment beds of other quarr...

This paper provides the results on spinel sampled from ailikites of Bolshetagninskii massif East Sayan region. The study aimed to determine history formation ultramafic lamprophyres Ziminsky complex. Spinel three dikes with different mineral compositions groundmass but similar textural and structural features (BTG 2/21, TGK 3, BTG 6/21) was analyzed. content main elements microcomponents in det...

The mineral ore potential of many mountainous regions of the world, like the Kurdistan region of Iraq, remains unexplored. For logistical and sometimes political reasons, these areas are difficult to map using traditional methods. We highlight the improvement in remote sensing geological mapping that arises from the integration of geomorphic features in classifications. The Mawat Ophiolite Comp...