Dark colors are not given to the sand by the traditional Lithuanian sand minerals – quartz and feldspar, but by completely different heavy minerals (their density is higher than 2.7-2.8 g/cm3). These include ilmenite, amphibole, pyroxene, biotite, rutile, zircon, magnetite, leucoxene and especially purple garnets.
“When such sand accumulates a lot, that is, when the concentration of heavy minerals is high, such places or accumulations are called alluvial deposits. Raw materials of tin, iron, and titanium can be extracted from heavy mineral deposits,” adds the geologist.
Ilmenite (iron titanium oxide FeTiO3) is a mostly black mineral used to make paints. Interestingly, the pigment itself – titanium oxide obtained from ilmenite – is white. Magnetite – iron oxide, iron ore. Rutile is a titanium oxide, like ilmenite, used in the production of white pigment. Zircon is metal zirconium raw material used in nuclear energy.
According to V. Minkevičius, deposits of heavy minerals can be found in Lithuania on the underwater slope of the Baltic Sea between Juodkrantė and Smiltynė, as well as between Klaipėda and Šventosia.
“Wave action and undertow currents help wash away the finer particles, clay and siltstone, while in the remaining sand the heavier minerals settle more easily and are more difficult to transport (quartz and feldspar particles are also removed because they are lighter). Thus, over time, sea currents and waves sort mineral grains according to size and weight,” explains V. Minkevičius.
Heavy mineral deposits began to be studied in the 20th century. in the 1970s and continued until the 1990s. Currently, no such research is being conducted.
Thus, the minerals in Lithuanian sand reveal a lot about the geological past. They show that our territory underwent complex geological processes that helped shape the current landscape, including glacial activity and the influence of marine currents.
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