Micro- And Nanoscale Graphite Cones and Tubes From Hackman Valley, Kola Peninsula, Russia

Ancient graphite in the Eoarchean quartz–pyroxene rocks from Akilia in southern West Greenland I: Petrographic and spectroscopic characterization

“…Most notable of these are sub-micron regions producing an enhanced 2D Raman feature compared to bulk graphite in the Akilia Qp rock, which are similar to curled graphite structures identified by Raman spectroscopy and visualized by SEM in CV3 carbonaceous chondrite meteorites (Fries and Steele, 2008) and to similar structures from a graphite-bearing pegmatite (Jaszczak et al, 2007). The enhancement of the 2700 cm À1 Raman feature compared to that of bulk graphite (Fig.…”

“…Graphene monolayers can also exhibit this kind of strong 2D overtone and experiments have shown that partial hydrogenation of graphene sheets can decrease the 2D intensity relative to the G-band intensity and significantly increase the D-band intensity (Elias et al, 2009). The naturally-occurring curled graphite structures attributed to spiral growth and conical patterns have been reported from alkaline pegmatites in the Kola Peninsula are associated with various mineralogically complex nepheline rock-types of enigmatic origin (Jaszczak et al, 2007). Graphite in this pegmatite occurs as coatings on crystals of aegirine, strontian fluorapatite, natronite, K-feldspar, micas, and other minerals.…”

Ancient graphite in the Eoarchean quartz-pyroxene rocks from Akilia in southern West Greenland II: Isotopic and chemical compositions and comparison with Paleoproterozoic banded iron formations

“…Nevertheless, these high-temperature experiments suggest that the graphite in the Vichadero BIF formed during a high-temperature event, most likely at the peak metamorphic temperature experienced by this rock. Apatite-associated graphite with spiral and conical structures has been documented by Raman spectroscopy and secondary electron microscopy in a mineralogically complex graphite-bearing alkaline pegmatite from the Kola Peninsula in northwest Russia (Jaszczak et al, 2007). While this rock is igneous in origin, its carbon is 13 C-depleted and was interpreted by Jaszczak et al (2007) to be biogenic in origin.…”

“…Apatite-associated graphite with spiral and conical structures has been documented by Raman spectroscopy and secondary electron microscopy in a mineralogically complex graphite-bearing alkaline pegmatite from the Kola Peninsula in northwest Russia (Jaszczak et al, 2007). While this rock is igneous in origin, its carbon is 13 C-depleted and was interpreted by Jaszczak et al (2007) to be biogenic in origin. The curled graphite structures found in the Vichadero BIF and the Akilia Qp rock are consistent with their high metamorphic grades, at the upper amphibolite and granulite facies respectively, but the minimum temperature and formation conditions at which these structures can form remains unknown.…”

Mineral-templated growth of natural graphite films

“…On a nano-scale, however, CM of a certain metamorphic grade can display strong structural variation and can contain a wide variety of sp 2 -bound carbon nano-structures including graphitic globules (Kovalevski et al, 2001), carbon onion rings (Beyssac et al, 2002b;Buseck and Huang, 1985), graphite cones (Jaszczak et al, 2003), rolled graphitic structures (Jaszczak et al, 2007), and curled graphite structures (Papineau et al, 2010). In general this can be related to the fact that organic precursor materials are heterogeneous in both molecular structure and chemical composition.…”