caa a22 4500 475813510 CHVBK 20180406123803.0 cr unu---uuuuu 170329e20000401xx s 000 0 eng 10.1007/PL00001104 doi (NATIONALLICENCE)springer-10.1007/PL00001104 Fractal Characterization of Particle Size Distributions in Chromitites from the Great Dyke, Zimbabwe [Elektronische Daten] [T. G. Blenkinsop, T. R. C. Fernandes] —Chromitite from seams in the early Proterozoic Great Dyke, Zimbabwe, has three types of microstructure. Grains in intact samples have an average of just over five slightly curved grain boundaries around each polygonal grain, and triangular-shaped triple grain junctions, some with grain boundaries intersecting at 120°. These features show adjustment to a minimum surface energy configuration. Samples with extension microcracks have smaller particles on average, which are more inequant and have a stronger preferred orientation than particles in the intact samples, due to fragmentation by impingement microcracking. Microfaults have still smaller average particle sizes, but more equant and less well orientated angular fragments, formed by sliding and rotation of particles after linkage between extension microcracks. Intact samples have a curved relationship on a log-log plot between cumulative numbers of particles and grain size. This particle size distribution evolves with strain to a linear, fractal relationship in the microfaults, with a fractal dimension of 2.8. The changes in particle size distribution are consistent with constrained comminution, and an additional process of selective fracture of larger particles. The degree of cataclasis is an important factor in determining chromite ore quality. Birkhäuser Verlag Basel,, 2000 Key Words: Cataclasis, particle size distribution, fractal, microfault, chromite nationallicence Blenkinsop T. G. Department of Geology, University of Zimbabwe, P.O. Box MP 167, Mount Pleasant, Harare, Zimbabwe., ZW aut Fernandes T. R. C. Institute of Mining Research, University of Zimbabwe, P.O. Box MP 167, Mount Pleasant, Harare, Zimbabwe., ZW aut https://doi.org/10.1007/PL00001104 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/PL00001104 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Blenkinsop T. G. Department of Geology, University of Zimbabwe, P.O. Box MP 167, Mount Pleasant, Harare, Zimbabwe., ZW aut NATIONALLICENCE 700 1- Fernandes T. R. C. Institute of Mining Research, University of Zimbabwe, P.O. Box MP 167, Mount Pleasant, Harare, Zimbabwe., ZW aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer