TITANIMBEARING- AND TITANIUMSILICATE SUBFILE

E.K. Vasil'ev, V.G. Evsyunin

Institute of the Earth's Crust, Siberian Department, Russian Academy of Science, ul. Lermontova 128, 664033, Irkutsk, Russia

Successful accomplishment of an identification of substantial composition of rocks and ores is possible by XRD, if appropriate database (DB) of reference standards (powder X-ray diffraction spectra of pure phases) are available. Many years ICDD forms universal PDF of inorganic and organic phases, minerals, frequently met phases, metals and alloys and so on. Sometimes specialised files are needed for solution of particular problems. In the laboratory of our Institute titaniumbearing- and titanium silicate DB for the identification of minerals in rocks has been founded. Minerals are named titanium silicates, if the titanium has appointed positions in their crystal structure. In titaniumbearing silicates titanium atoms replace a part of another atoms (not more 50%) in their positions.

This subfile has been formed out of the PDF data, other literature data and XRD patterns, prepared in the laboratory. Thus powder XRD spectra of minerals are reference standards. A peculiarity of these data consists in that they have been determined from natural compounds (minerals), which have arose in a matrix of complicated chemical composition by uncontrolled physical and chemical conditions and different geological environments. Their actual structure differs from average structure of synthetic analogues because of variations of chemical composition, presence of admixture defects, reflected genetical features of minerals. It is reflected on powder diffraction patterns as fluctuations of d, I magnitudes and decrease of line number.

Peculiarities of mineral powder diffraction patterns mentioned introduce some difficulties in the interpretation process. In addition published numerical data (d, I and unit cell parameters) have been presented in a refined form without sufficient information on an experimental treatment, that makes an estimation of these data reliability difficult. Nevertheless this subfile allows to carry out the identification of mineral composition of studying samples confidently.