The present paper presents the results of further investigations undertaken to determine the optical symbols of various minerals. The table provides the selected observations in mica plates. At the end of the article, more detailed data are provided regarding observations in simple and combined plates, as well as the characteristics of individual members of the group under consideration (muscovite, alomite, biotite, phlogopite, etc.).
In his article “Image of the structure of a crystal with vectorial circles” Prof. E.S. Fedorov outlines a graphical method for finding the densities of meshes of crystal faces (more precisely: the squares of the densities of the corresponding meshes). Anyone who has dealt with determining the densities of meshes of faces using this method knows that in this case one should make some constructions, not particularly complex, but nevertheless quite time-consuming.This article aims to show how the task can be simplified by reducing drawing work to a minimum.
A sample of the rare mineral Hambergite from a new deposit on the island of Madagaskar was sent to the Museum of the Mining Institute from the Bohm Mineralogical Office in Vienna. The article presents research data on a rare mineral and a description of the original figures on some fusion fragments.
From the Museum of the Mining Institute, a sample No. 169/3 with the label: “Bronzite from the river Slyudyanka” was transferred for research in the Mineralogical Cabinet. Two thin sections made from it showed that the sample is a rock, which, in fact, contains, as a component, rhombic pyroxene, close to bronzite. The rock itself presents some features in its composition and structure, which force to attribute it to the type of drusite rocks.
Prof. Fedorov proposed a method for determining the nature of the dispersion of optical axes on a universal table and outputting the optical symbol of a mineral. Currently, at the Mineralogical Institute, a number of measurements have been taken using this method. This note presents the results of the first (still few) observations.
