Rare Earth Element Patterns of Carbonado and Yakutite: Evidence for Their Crustal Origin

Ken Shibata*, Hikari Kamioka, Felix V. Kaminsky, Vassili. I. Koptil and Darcy P. Svisero
Geological Survey of Japan, Tsukuba 305, Japan
Central Research Institute of Geological Prospecting for Base and Precious Metals, 113545, Moscow, Russia
Institute of Geosciences, University of Sao Paulo, C. P. 20899, Sao Paulo, Brazil
*Present address: Department of Earth and Planetary Sciences, Nagoya University, Nagoya 464-01, Japan.

Abstract: Carbonado and yakutite are both porous aggregates of polycrystalline micrometre-size diamond, with very different characters from those of monocrystalline diamond. The genesis of carbonado is very controversial, whereas yakutite is thought to have been formed by meteorite impact. Neutron activation analyses of trace elements in carbonado and yakutite indicate that their rare earth element (REE) abundance patterns have common characteristics: heavy REEs are not much depleted and a negative Eu anomaly is observed. These patterns are quite different from those of kimberlite and monocrystalline diamond and are similar to those of crustal materials such as shale, supporting the hypothesis of a crustal origin for carbonado and yakutite.

Keywords: carbonado • yakutite • diamond • florencite • rare earth element • crust

Mineralogical Magazine; December 1993 v. 57; no. 389; p. 607-611; DOI: 10.1180/minmag.1993.057.389.05
© 1993, The Mineralogical Society
Mineralogical Society (www.minersoc.org)