Rudy darniowe okolic Torunia

Abstract

THE MEADOW ORES OF THE TORUŃ REGIONThis paper deals with the examination of four meadow ore samples from loealites: Rubinkowo (suburb of Toruń), Glinno Wielkie, the Zielona forest-district, and Bobrowniki on the Vistula, - all of them situated near Toruń. Within these studies the author carried out field investigations, chemical analyses of the ores, and identifying x-ray examinations. He also discusses the mineral composition of these ores on the basis of literature dealing with this subject-matter, and comments of the origin of the ores found at the individual localities.All the investigated ores revealed a far-reaching differentiation, even within one locality. These differences are due to different genetic conditions, especially as to pH values and ion admixtures which exert a decisive effect upon the trend of crystallization of the Fe hydroxides, i.e. on the course of ageing of these compounds. On the basis of his considerations of this ageing process, the author distinguishes the following stages of crystallization:1. a brown, amorphous iron hydroxide, commonly called meadow ore, with outcrops mainly at Bobrowniki. This ore consists of nests of young, unaltered Fe hydroxides, preserved due to the presence of organic substance and Ca+ + ions.2. an α-ferrous hydroxide, an intermediate member between the above amorphous hydroxide and α-ferrous hydrate. This member occurs probably in the ores from Bobrowniki, Rubinkowo and Glinno, in the shape of orange-coloured and brown crystalline concentrations.3. an α-ferrous hydrate Fe2O3 · H2O, present chiefly in the ores from Bobrowniki and, partly too, those from Rubinkowo and Glinno; this ferrous hydrate appears as a yellow goethite coating.Part of the ore from Bobrowniki has crystalized out as hematite, thus presenting an interesting example of mineral differentiation of one deposit, depending on physico-chemical conditions and, especially, on its ion admixtures. The ore from the Z:elona forest-district consists chiefly of amorphous psilomelane.The presence of all the above minerals has been corroborated by x-ray examination.