Un échantillon de l'orthoamphibole lithique holmquistite a été examiné par spectroscopic Mössbauer, et son spectre infrarouge dans l'intervalle d'absorption d'hydroxyle (3 800-3 500 cm⁻¹) a été déterminé. Les résultats qualitatifs et quantitatifs sont présentés, et les occupations des sites sont confrontées à celles de précédentes mesures aux rayons X.
Les spectres infrarouges de plusieurs anthophyllites ont été mesurés dans la région de la vibration de valence du groupement OH (3 800-3 500 cm⁻¹). Les bandes principales présentent une structure hyperfine jusqu'ici inconnue.
ABSTRACT. Infra-red spectra of gedrites have been measured in the hydroxyl region (3800 3500 cm-1). The spectra can be related to those of clinoamphiboles and of anthophyllites, and show the normal amphibole pattern of peaks whose intensities reflect the proportions of different cations in the adjacent octahedral sites. The absorption is weak especially in spectra of gedrites high in AI. Hyperfine splitting of peaks has been observed in anthophyllite spectra (Law, 1981) but the extent of hyperfine splitting in gedrite spectra is limited. The underlying baseline absorption, upon which the hydroxyl peaks are superimposed, becomes steeper and more awkward to estimate in gedrites. Some higher frequency peaks, probably arising from unit cells with A sites occupied by Na, are observed.
Fitted M6ssbauer spectra are presented for a set of anthophyllites and gedrites. Despite their complexity it is possible to obtain fits for gedrite spectra and the M6ssbauer parameters are consistent with results for anthophyllites from this and previous studies. At least three doublets are required to fit the Fe 2+ absorption in gedrites; there is no single model at present to explain the behaviour of the spectra. Fe 3+ absorption is also resolved. K E Y W O R D S: orthoamphiboles, M6ssbauer spectra, anthophyllites, gedrites.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.