.... The interaction of carbonates with metals is one of the mechanisms of the release of elemental carbon and the formation of diamond. These processes are also accompanied by carbon isotope fractionation and can result in a significant isotopic heterogeneity of mantle carbon. In this work we study the partitioning...

...A.G. Sokol; O.A. Koz’menko; A.N. Kruk; S.F. Nechepurenko Abstract —The composition of the fluid in carbonate- and chlorine-bearing pelite was experimentally studied at 3.0 GPa and 750 and 900 ºC, using the diamond trap method. The results of inductively coupled plasma atomic-emission spectrometry...

...Yu.N. Palyanov; Yu.V. Bataleva; Yu.M. Borzdov; I.N. Kupriyanov; D.V. Nechaev Abstract —Experimental studies aimed at determining the conditions for the formation of diamond and graphite as a result of the redox interaction of reduced mantle rocks and oxidized rocks of the slab in a wide temperature...

... of magnesian carbonate, kyanite, and coesite, a decrease in Mg contents in the recrystallized garnet, and the formation of carbonate, silicate, and oxide inclusions in it. Under these conditions, crystallization of metastable graphite and growth of diamond on the seed at ≥1250 °C were observed...

...-bearing metasomatic agents and their role in the global carbon and sulfur cycles and in the processes of natural diamond formation. Experimental studies aimed at the estimation of sulfur solubility in carbonate melts under lithospheric mantle conditions were carried out on a multianvil high-pressure...

...Geoffrey H. Howarth; Beth Kahle; Philip E. Janney; Richard Kahle; Anton Du Plessis; Stephen H. Richardson; John J. Gurney Abstract Diamonds can form within eclogite (remnants of ancient subducted oceanic crust) in the subcontinental lithospheric mantle (SCLM), pieces of which may...

...Nicole A. Meyer; Thomas Stachel; D. Graham Pearson; Richard A. Stern; Jeffrey W. Harris; Michael J. Walter Abstract Characterizing compositional heterogeneity in Earth’s lower mantle is critical to understanding its dynamics. Three low-nitrogen diamonds from Koffiefontein (South Africa), containing...

...Felix V. Kaminsky; Dmitry A. Zedgenizov Abstract Merrillite, ideally Ca 18 Na 2 Mg 2 (PO 4 ) 14 (Dana No: 38.03.04.04; Strunz No: 08.AC.45), an analog to synthetic tricalcium phosphate β-Ca 3 (PO 4 ) 2 , was identified as an inclusion in lower-mantle diamonds from the Rio Soriso area, Brazil...

... in a diamond from the Gahcho Kué mine in the Northwest Territories, Canada. It occurs as brown, translucent single crystals with an average maximum dimension of ~80 μm, associated with rutile and calcite. The luster is adamantine, and the fracture conchoidal. Heamanite-(Ce) is the K-analog of loparite-(Ce...

...Evan M. Smith; Mandy Y. Krebs; Philomena-Theresa Genzel; Frank E. Brenker evan.smith@gia.edu krebs@ualberta.ca Copyright © 2022 by the Mineralogical Society of America 2022 Mineralogical Society of America Open access: Article available to all readers online. Diamonds...

.... Optical spectroscopy is a valuable non-destructive technique for the study of many materials. For diamond it is used for fundamental research to enhance our knowledge about this remarkable material; it is used in gem-testing laboratories to determine whether a diamond is natural or synthetic and whether...