Vol 2 Iss. 3

The work that was carried out this summer in the platinum-bearing region aimed at finding out the direction in which exploration for primary platinum should be carried out. The only goal of our work was to collect material for the petrographic characterization of the area. Samples were taken from outcrops mainly along quarter-section lines, roads and ravines. The results of processing the collected material represent the bulk of this work. In another part, I shall focus on the discovered platinum deposits.

In this article, I severely narrow my task and do not even mention the various geometric systems and their combinations that offer a means to solve it; I focus exclusively on considering a single system of the 4th order on the plane, which most directly corresponds to the essence of the matter. This system is a direct extension of the system of parallel vectors, namely, extended in the sense that vectors, as elements of the system, may also be non-parallel. It is clear that this condition elevates the system by one order, making it precisely a system of the 4th order (corresponding to the geometry of 4-dimensional space).

In spring 1907 and 1908, the authors of this note participated in a geological excursion along the northern coast of Lake Ladoga. The excursion began with an inspection of the Imatra Waterfall and the surrounding rocks, which exhibit characteristic signs of the glacial period. From Imatra, we traveled to the town of Serdobol and from here we set off on foot along the shore of Lake Ladoga, getting acquainted along the way with the rocks of this area and with two ore deposits, Välimäki and Pitkäranta, the latter being the final destination of our trip. Without having in mind to describe all the material, for our brief note we selected only the rock samples that we gathered along the way from the town of Serdobol to the Välimäki iron mine inclusive, the most interesting from a petrographic point of view.

In the summer of 1901, I managed to inspect the Kerch mines, where I obtained a fragment from a large barite specimen with the note that it was found in a mine located near the plant. The specimen in its original size was about 2 kilos in weight and had the shape of a mushroom; completely dense both in its central part and at the edges; wax-yellow in color with a white streak, translucent in small pieces and transparent in thin fragments; the pereferical layer about 3 mm thick is yellowish-white and cloudy. The structure is radiant. March 20, 1909

The presence of vesuvianite, this characteristic contact mineral, together with garnet, makes the rock particularly interesting from the point of view of the genesis of the Mount Magnitnaya ore deposit. It is hardly possible to attribute a hydrochemical origin due to weathering processes to such a rock as the one described; on the contrary, we see clear evidence of contact metamorphism in it.

A hemisphere with a radius of 5 mm and a diametral plane (110) (the cleavage plane) was cut from a cleavage fragment of calcite. This hemisphere, attached with wax to a glass hemisphere of the same diameter, was suspended on a thread in a supersaturated NaNO3 solution. Prior to this, to clean the surface of the calcite hemisphere, the sphere assembled as described above was immersed for several seconds in a dilute hydrochloric acid solution.

The crystals of this mineral from the Museum of the Mining Institute had already been systematically described by me in a special article. Recently, the museum has received two new interesting small crystals of this mineral. What is most striking is their extraordinary thinness, reaching 0.1 mm with a planar dimension larger than a square centimetre. With such extreme differences, it is especially instructive to raise the question of the existence of a relationship between form and combination.

A. E. Kupffer, while crushing the rock from San Zenito in California, which contains almost black and rather large neptunite crystals in abundance, isolated, among other things, an excellently formed crystal of a rather deep blue color, developed in combinations typical of a rhombic crystal with four very sharp pyramids (see the article).

Using the hemispheres of potassium alum I had and the corresponding cavities in a large crystal, I wished to test how impurities in the solution, which do not exert a decomposing effect on the solute, influence the process. A likely conclusion is the formation of faces, although of poor quality, with more complex symbols on the spherical surfaces, but of such small size that reflections are generally undetectable, and only some of them begin to become detectable due to impurities that improve crystallization.

Vicinaloids, or vicinal surfaces, are those surfaces that, while forming the true faces of crystals and are very close to planes, are actually not planes, but highly complex and varied curved surfaces. But if, in general, during crystal growth, clustering, that is, the non-parallel staking of particles occurs chaotically, that is, equally in all directions (complete disorder of clustering), then one cannot deny the possibility of the existence of causes that disrupt this complete disorder and produce partial disorder.

The basis of the modern concept of the regularity in the formation of faces lies in the principle of correspondence between the order of importance of faces (manifested both in their very appearance and in their size) and the order of their reticular density. This principle is derived from experience as a statistical law, that is, not as an exact law that manifests always and unconditionally, but as a regularity, which manifests itself in a significant majority of cases. The exceptions that we generally find in experience by no means exclude the idea of the absolute significance of the order of the density of faces, but they indicate that the formation of faces, in addition to this absolute factor, is influenced by other factors, the significance of which has not yet been expressed numerically; and these factors may be quite numerous, since the degree of formation of particular faces is also influenced by various external, partly difficult-to-detect conditions.

I would like to note not only the diversity evident from these tables, important for crystallochemical analysis, but also the importance of the intermediate minimum that is observed for the principle numbers. It should be noted that in isotropic complexes, the distinction between tetragonal-like and trigonal-like disappears and, in general, crystals could be classified as pseudo-cubic. However, if we were to add genuine cubic crystals to them, we would obtain a special cluster of crystals for this particular gap, which would be an unfavorable factor for the analysis, and it turns out that just in this gap, some rarefaction in the distribution naturally occurs.