Vol 38 Iss. 2

A universal geometrical doctrine of crystal shapes of both ordinary and complicated crystals (crystal skeletons, growth pyramids, induction surfaces, regular aggregates, etc.) has now been completed.

The present communication completes the series of articles by V. I. Mikheev and I. I. Shafranovsky devoted to the complete derivation of all possible rib forms.In the derivation of simple rib forms of cubic singony, we first of all proceed from possible facet combinations. For this purpose we had to enumerate all possible pairwise combinations separately for each of the five kinds of symmetry. The symbols for such combinations are summarized in the table, where the upper horizontal line contains the symbols of the faces of the initial forms, in the planes of which lie the derived edges. The vertical line contains combinations of symbols of those faces, the intersection of which results in edge forms. A number of rib forms with a relatively small number of included edges are the result of intersection of faces of one simple form (from among those indicated in the upper horizontal row of the table); for example, the twelve- tsatyrebernik of a cube.

Two polymorphic modifications of iron oxide hydrate are known in nature - goethite a-FeO(OH) or HFeO₂ and lepidocrocite y-FeO(OH). However, until now in the literature and practice for loose ferruginous formations the name hydrogetite is common, which, according to E. J. Rohde and B. K. Brunovsky, represents a hydrate of iron oxide. K. Brunovsky, is a solid solution of zeolite-type water in goethite. The presence of such water should cause an increase in the interplanar distances and, consequently, in the unit cell parameters of the so-called hydrogetite (the same applies to hydrohematite). But, as X-ray radiometric studies show, the changes in the values of interplanar distances are so insignificant that they are within the error of experience. Such friable formations, apparently, are finely dispersed goethite containing a considerable amount of adsorbed water. Debaeograms of hydrogetite differ from ordinary goethite only by strong blurriness and width of diffraction lines.

Simple rib shapes of trigonal and hexagonal syngonies. For crystals of trigonal and hexagonal syngonies we have derived 90 simple rib shapes. In order to classify them, we will use the numbering and special symbols adopted for tetragonal forms.

At present, work is underway to compile a radiometric identifier of metals and alloys. For each crystalline substance a characteristic X-ray diagram is determined. The study of X-ray images allows identifying the same substances and distinguishing between dissimilar ones. The very process of determining substances consists in obtaining and calculating X-ray images and then comparing the results with previously taken reference X-ray images of known substances. The totality of reference X-ray radiographs of metals and alloys and will constitute the X-ray determinant of metals and alloys.

Several samples of schlich platinum from a differentiated gabbro-diabase intrusion located in the Taimyr National District were studied. The schlich platinum was preliminary divided into three fractions: electromagnetic (EMF), magnetic (MF) and strongly magnetic (SMF).

Nineteen samples of ilmenite were studied (Table 1), of which one sample 436a was a krichtonite, i.e., ilmenite almost free of magnesium, from a differentiated trap intrusion on the Alamzhakh River, and the remaining 18 samples were collected with the help of an electromagnet from kimberlite flows from the Zarnitsa and Mir diamondiferous pipes (Yakutia). From crushed ilmenite, individual fractions were sampled at different current strengths in the electromagnet in the range 0.4-1.2 a every 0.1 a. Two such series of samples of 9 fractions each were selected. The first series from I-1 to I-8 and I-19 is represented by ilmenite from the “Mir” tube, the second - from I-9 to I-28 from the “Zarnitsa” tube. Specific gravity was determined for all selected fractions.

The following tasks were set before the X-ray radiometric study: to establish amorphous or crystalline nature of samples; to find out whether there are significant structural changes for different samples of gummites, isolated by morphological features into varieties; to identify, if possible, the reasons for the structural 'features of different samples; to give X-ray radiometric standards for gummites, comparing them with the results of X-ray radiometric studies of these minerals available in the literature; to trace the nature of changes in minerals at the and The work was carried out in the X-ray radiometric laboratory of the Fedorovsky Institute at the Leningrad Mining Institute in 1948.

The X-ray laboratory of the Leningrad Mining Institute, headed by V. I. Mikheev, systematically carried out studies to determine the material composition of various products and mineral formations. These works were carried out at the request of various industrial and scientific organizations.

When studying the scientific works of V. I. Mikheev, one is first of all struck by the exceptional purposefulness and clarity of the main line of his work. This line is a direct continuation and development of the works of his teacher A. K. Boldyrev, and thereby the works of E. S. Boldyrev. С. Fedorov. That is why in our eyes V. I. Mikheev is an outstanding representative of the Fedorov school, the crystallographic-mineralogical school of the Mining Institute. In order to trace the defining features of V. I. Mikheev's creative path, it is necessary to recall some characteristic moments from his biography.