Preliminary investigations of paragonite in marbles from sivec, north Macedonia

This paper presents preliminary results of investigation of the paragonite crystals in marbles from Sivec. Investigated samples were analyzed by IR, SEM and XRD methods. Paragonite from Sivec has light apple-green colour. It occurs in small nodules found generally in fine-grained parts and in cleavages of the white dolomitic marble. Paragonite crystals are greasy to the touch. The luster of its small scales resembles that of the sericite. Crystals are thin and tabular II {001}, commonly fine scaly. Crystal system is monoclinic, 2/m.Cleavage is perfect II {001}. The presence of paragonite indicates that the muscovite is saturated with the sodium component and that the assemblage lies on a section of the multi component solvus between the muscovite and paragonite end members. In this case we have transition from muscovite to paragonite. The concentration of Na increases (0.87–4.52), while the concentration of K is decreasing (4.62–0.32). The most intense registered maxima in the studied X-ray powder diagram were compared with the corresponding maxima in the diagram of paragonite 1M, ICDD00 0420602. The unit cell parameters obtained using the main reflection lines of X-ray diffraction are: a = 5.124 Å; b = 8.890 Å; c = 19.324 Å; β = 94.06°; V = 878.1 Å3. (author)