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Ilmenite in soil forming from a Brazilian amphibolite
Author(s) -
DORIGUETTO A. C.,
GOULART A. T.,
JESUS FILHO M. F.,
FABRIS J. D.,
SANTANA G. P.
Publication year - 1998
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1046/j.1365-2389.1998.4940541.x
Subject(s) - ilmenite , spinel , geochemistry , geology , mineral , mössbauer spectroscopy , mineralogy , chemistry , materials science , metallurgy , crystallography
Summary Ilmenite‐rich samples were obtained by chemical extraction methods from materials collected from a soil developing on an amphibolite and from its altered parent rock. The soil ilmenite of this mantle was found to be inherited from the rock, but its composition varied significantly from one soil fraction to another and according to its mineralogical association. Unit cell parameters are smaller than those of pure ilmenite: the a ‐dimension of the hexagonal structure varies from 0.5076 ± 0.0004 to 0.5083 ± 0.0007 nm. Mössbauer patterns at room temperature reveal that this mineral, which is most often associated with the iron‐rich spinel phase, actually corresponds to a member of the haematite–ilmenite series having the general formula x FeTiO 3 .(1‐ x )Fe 2 O 3 , with 0.83 ≤ x ≤ 0.95. There is a correlation ( r = 0.95) between x , the molar fraction of FeTiO 3 , and the a ‐dimension of the unit cell.