Chlorofeit (saponit żelazisty) z Wisznie koło Włodawy

Irena Kardymowicz




The occurrence of basic vulcanites in the Polish Lowland was reported for the first time in 19158, when these rocks were drilled at Wisznice, at a depth of 375.3 to 416,2 m. It was on the walls of basalt fissures (depth 408.3 m.) that a chlorite- like mineral was found in the form of fine-crystalline aggregates, characterized by radial-fibrous arrangement, silky polish, and greenish-black colour. This mineral is, brittle to the touch and crumbles easily into fine flakes and scales. It shows a high content of low-temperature water; when heated, it turns yellowish brown and becomes magnetic. The mineral dissolves in hot hydrochloric acid and form a yellow solution with floating silica flakes. The specific weight of this mineral is 2.29 G/cm3; its refractive index varies from 1.540 to 1.577 (measured in immersion fluid).

Table lA shows the chemical composition of the mineral, Table 2, – it crystallochemical formula. The latter shows the characteristic ratio Si: Mg as 4: 3; on this basis the mineral from Wisznice can be identified as ferruginous saponite (chlorophaeite in English nomenclature). The same tables present chemical properties of some saponites and chlorophaeites from other countries; they correspond to those of the mineral from Wisznice.

The results of thermal curves (Fig. 2) of the mineral in question correspond to those obtained in the case of the mineral compared here (Figs. 3–5). X-ray analysis of the mineral from Wisznice shows the greatest intensity of lines characteristic of chlorophaeite (table 3).

The geological conditions in which the mineral occurs that it belongs genetically to hydrothermal solutions and it chemical properties are closely connected with those of the original basalt rock (Table 1B)

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