Sandimirov S.S. Geochemisrty of water-rock interaction in the area of the Khibiny alkaline massif. Geochemisrty International. 2007, T.54, №11, p. 1103-1110.

GEOCHEMISTRY OF WATER-ROCK INTERACTION 1107 Fig. 2. X-ray diffraction patterns of ground apatite-nepheline ore before (bottom) and after (top) a three-month experiment with water. Ap, apatite; Ne, nepheline. The diffraction patterns were recorded at the Geological Institute of the Kola Scientific Center, Russian Academy of Sciences, analyst T.A. Selivanova 0.5 |nm are better preserved in alkaline water than parallel columns. The composition of water at the sam- nepheline particles of the same size. pling site is shown in Table 1 (an. 7 and 8). Our results showed that the interaction of the min- The investigation of the inorganic matter of bottom eral matter of Khibiny rocks with natural waters is a sediments is a difficult task, because it is dominated by complex process involving weathering, slow dissolu- nanoparticles [22]. The samples are dark brown muds tion of nepheline and feldspathoids, rapid dissolution of cementing during drying. Their chemical compositions fine mineral particles, formation of amorphous phases were analyzed on an MS-46 electron microprobe (ana- at the expense of the decomposition of fine nepheline lyst Ya.A. Pakhomovskii), using the aforementioned particles, and possible activation of buried waters. Of course, this list is not complete. MINERAL COMPOSITION OF BOTTOM SEDIMENTS AT THE REGION OF INDUSTRIAL WATER DISCHARGE FROM THE CONCENTRATING MILL INTO LAKE IMANDRA The apatite-nepheline deposits of the Khibiny Mas­ sif are the greatest source of phosphates. Apatite con­ centrate is produced by flotation with crushing up to the <0.3-mm fraction. This process results in the influx of huge masses of mineral ore particles smaller than 1 |nm into the environment. After ore crushing, the mill tail­ ings containing the finest fraction are stored in a depos­ itory of sands, which remained after apatite extraction and supply industrial wastes into Lake Imandra. The Belaya River basin is mainly located outside the Khibiny Massif, among the Proterozoic volcanosedimen- tary country rocks of the Imandra-Varzuga Formation and Archean granite gneisses. The bottom sediments of Lake Imandra were sampled near the mouth of the Belaya River, which receives industrial waters from the concentrating mill of ОАО Apatite. The top layer of the lacustrine sediments 7.8 cm thick was sampled in two wt % 30 г 20 10 A120 3 K20 Fig. 3. Main changes in the composition of ground apatite- nepheline ore (1) after its storage in water for three months (2). The finest suspensions were partially removed with water. Analyst Ya.A. Pakhomovskii, Geological Institute, Kola Scientific Center, Russian Academy of Sciences. GEOCHEMISTRY INTERNATIONAL Vol. 45 No. 11 2007