DIFFRACTION AND NONDIFFRACTION STUDIES OF K- FELDSPARS AND HIGH-Ca PLAGIOCLASES. Moroz T.N., Grigorieva T.N., Lesnov F.P., Arkhipenko D.K. United Institute of Geology, Geophysic and Mineraloqy, Siberian Branch RAS, 630090 Novosibirsk, Russia

The determination of degree of order and composition in a large collection of different genesis K-feldspars and the high-Ca plagioclase samples from mafic rocs of some abissal and middle-abissal massifs approached as ussually by means of X-Ray powder diffraction has been additionally carried out by vibration (Raman and infrared-IR) spectroscopy methods.

The procedure of structural feature determination extended over a series of sanidine-adylar-microcline has been developed according to nondestructive laser Raman spectroscopy data sensitived to intermediate or long-range order. Unpolarized Raman spectra were measured in right-angle scattering geometry using Jobin Ivon spectrometer RAMANOR U 1000 with single channel detection system. 514.5 nm line of Ar⁺ ion laser was used as the excitation source. Fluorescence has been a serious impediment to observation of Raman spectra of the samples. Different regimes of recorder Raman spectra and laser produced fluorescence spectra were selected.

The relationship between fluorescence and factors of mineral formation can be followed. It is discussed as possible to use the halfwidth, peak position, the splitting of Raman line of feldspars as typorphic property which allows distinguishing mineral grains with different conditions of original. A comparison between data obtained by means of Raman spectroscopy and results of X-ray diffraction and IR spectroscopy estimated showed that they were in good agreement.

This work was supported in part by RFFI grant N 94-05-16537a