Vol 12 Iss. 1

In the field of geological and mineralogical work, X-ray measurements can have a wide and varied application. In X-ray measurements, there are several methods for studying crystalline matter. The main methods are: the Laue method, the crystal rotation method, the Debye‑Scherrer‑Hall method (or powder method), and the Bragg method. To determine a given mineral, it is necessary to grind it into powder, obtain a Debyeogram from it and compare it with the Debyeograms of known minerals that could be presumed to be the given mineral. Similarly, when determining the mineral composition of a mixture, a Debyeogram is obtained from it and this latter is compared with the Debyeograms of those minerals whose presence was expected in the mixture. It follows that to apply this method it is necessary to have Debyeograms of known minerals as standards, with which the Debyeogram of the analyzed substance is compared. In each individual area of application of the X‑ray analysis method, a whole series of standard Debyeograms for a number of suspected substances must be prepared. At present, it is necessary to begin compiling a determinant of substances based on their Debyeograms, similar to a determinant of crystals based on goniometric data.

The aim of the present work which was begun after a similar work of V. Michelev (1) was to obtain the standard x-ray powder diffraction patterns of minerals and to determine the mineralogical composition of melted rocks by means of x-ray examination. The methods of optical determination of the mineralogical composition of the melted rocks are not always satisfactory, and therefore the x-ray examination is for the present time a irreplaceable. The x-ray powder method may be applied for the determination of the mineralogical composition of a casting and x-raying is to used to disclose their defects. In order to identify the x-ray diffraction patterns of melted rocks with known minerals we had to obtain as many films of these minerals as possible. By means of the x-ray powder method we have received the diffraction patterns of the following minerals: almandine (Fe₃Al₂Si₃O₁₂), grossular (Ca₃Al₂Si₃O₁₂), actinolite H₃Ca₈(Mg, Fe)₅(SiO₃)₈, hornblende (OH, F)₂ (Na, Ca, K, Mn)₂₋₃ (Mg, Fe, Ti, Mn, Al)₅ (Si, Al)₆O₂₂, synthetic spinel (MgAl₂O₄) and two of melted rocks. In order to avoid some experimental errors in the investigation of minerals it was necessary to have the diffraction patterns of pure specimens and those of specimens with admixture of rock salt (NaCl).

The paper describes the distribution of structures and the mineralogical composition in the castings which have been made from a melt of Ropruchey dibase and Segozersk picrite in the form of muffs (couplers). There are stated some considerations concerning the interdependence between the structures and the thermal regime.

By means of the (Debay-Scherrer-Hull) powder method have been investigated fourteen minerals of the class of oxides. In the present paper are given exact values of the interplanar distances and relative intensities of lines, for the following minerals: thorite, cassiterite, polyanite, ilmenorutile, wood-tin, pyrolysite, thorianite, uraninite, nasturan, senarmonitite, arsenolite, claudetite and Sb-ocher. The tables given in this paper may be considered as material for "Röntgenometrical Determinative Tables of Minerals". Besides, there are also given models of tables and methodology of preparation of powder diagrams which will be useful in the future work as example on the composition of "Röntgenometrical Determinative Tables of Minerals".

This work is the first part of a study and deals mainly with issues related to heat treatment. The second part, which will present petrographic analysis and mechanical properties of cast stone, will be published separately and will be a direct continuation of the first part. The reader will find here a description of certain transformations occurring in specific temperature intervals, which the author has termed critical points and which have been discovered for the first time in materials made from molten rocks. A fairly detailed analysis of heating and cooling rates near the critical points is presented, allowing the author to draw a number of conclusions that have great practical significance and can introduce substantial changes into all technological processes of stone casting.