MINERALOGICAL AND CHEMICAL CHARACTERIZATION OF VIVIANITE OCCURRENCE IN SEDIMENTS OF THE PELAGONIA BASIN, REPUBLIC OF MACEDONIA

Abstract

Crystalline vivianite occurrences in the Republic of Macedonia are very rare. It can be seen in the sediments of the Pelagonia basin, particularly in the tripolites of the Suvodol locality. For research on our sample were used the following four methods: infrared spectroscopy IR, scanning electron microscopy (SEM), inductively coupled plasma atomic emission spectrometry AES-ICP and X-ray diffraction. Тhe crystals of the vivianite are prismatic and tabular with a different length of several cm across. The colour of studied vivianite is greenish blue. The streak is pale bluish, but the colour is soon changing dark blue due to oxidation. Lustre is pearly. Very often can be seen distinct cleavage planes parallel to {010}. The density determined by pycnometer is 2.62 g/cm3 . Hardnes is 1.5–2. The concentration of the oxides is: FeO 42.89%, P2O5 28.67%, MnO 2.50%, MgO 0.34%. Also were detected the following trace elements: Cd, Cr, Ni, Ba, Sr, Bi, Zn, Pb, Cu Ag, Co, In, Tl, Ga and Li. The most intense registered maxima in the studied powder pattern [d values (in Å), I] are: 6.81 (100); 3.22 (6); 2.71 (6); 2.33 (5); 1.68 (12); 1.34 (5).The unit cell parameters obtained using the main reflection lines of X-ray diffraction are: a = 10.03 Å, b = 13.50 Å, c = 4.72 Å, β = 102.52°, V = 625.79 Å3. The results of all analyses showed that the studied sample is vivianite.

Key words: vivianite, IR; SEM-EDS; AES-ICP; XRD