Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Résumé Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Jaszczak, J. A. Articles by Gogotsi, Y. Search for Related Content GeoRef GeoRef Citation

MICRO- AND NANOSCALE GRAPHITE CONES AND TUBES FROM HACKMAN VALLEY, KOLA PENINSULA, RUSSIA

John A. Jaszczak^1,, Svetlana Dimovski^2,, Stephen A. Hackney³, George W. Robinson⁴, Paolo Bosio⁵ and Yury Gogotsi⁶

¹ Department of Physics and the A. E. Seaman Mineral Museum, Michigan Technological University, Houghton, Michigan, 49931–1295, USA
² Department of Materials Science and Engineering and A.J. Drexel Nanotechnology Institute, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, USA
³ Department of Materials Science and Engineering, Michigan Technological University, Houghton, Michigan, 49931–1295, USA
⁴ Department of Geological and Mining Engineering and Sciences, and the A. E. Seaman Mineral Museum, Michigan Technological University, Houghton, Michigan, 49931–1295, USA
⁵ Via G. Mameli 52, I–21010 Cardano al Campo (VA), Italy
⁶ Department of Materials Science and Engineering and A.J. Drexel Nanotechnology Institute, Drexel University, 3141 Chestnut St., Philadelphia, Pennsylvania 19104, USA

E-mail address: jaszczak{at}mtu.edu

We describe several unusual forms of natural graphite from an alkaline pegmatite that cross-cuts rischorrite in the Hackman Valley, Khibiny Massif, Kola Peninsula, Russia. The graphite occurs macroscopically in two forms: as spherical aggregates up to 2 cm in diameter of friable, radially aligned fibers ~20 µm in cross section, and as fine-grained surface coatings in cavities covering aegirine, strontian fluorapatite and K-feldspar. Optical microscopy and field emission scanning electron microscopy (FESEM) show that the fibers are actually hollow channels whose walls are composed of tabular crystals of graphite greatly elongate in the direction of the fiber axis and with their basal planes oriented parallel to the channel walls. Inside and among the channels occur rolled graphitic structures (RGS): scrolls, tubes, and cones up to 2 µm in diameter and up to 15 µm in length. The fine-grained graphite coatings on the surfaces of cavities, on the other hand, consist almost solely of micro- and nanoscale RGS. The largest of the RGS are hollow scrolls, with the c axis predominantly perpendicular to the scroll axis. These are usually cigar-shaped but can also be more tubular. Conical RGS occur at the micro- and nanoscales. The nanoscale cones tend not to be hollow and may have a cone–helix structure. Transmission electron microscopy (TEM), Raman spectroscopy, and FESEM indicate that the RGS are composed of well-ordered graphitic layers but are commonly coated by amorphous carbon. The morphologies and paragenesis of these unusual graphite forms suggest a possible hydrothermal origin.

Keywords: graphite, electron microscopy, crystal growth, crystal morphology, Raman spectroscopy, stable carbon isotopes, Khibiny massif, Russia.

This article has been cited by other articles:

				M. Fries and A. Steele Graphite Whiskers in CV3 Meteorites Science, April 4, 2008; 320(5872): 91 - 93. [Abstract] [Full Text] [PDF]