Turkish Borate Deposits: Geological Setting, Genesis and Overview of the Deposits

Abstract

Boron is widely distributed in the earth’s crust and the element boron does not exist freely by itself in nature, rather it occurs in combination with oxygen and other elements in salts, commonly known as borates. Boron is a rare element in the Earth’s crust, but extraordinary concentrations can be found in places. Four main continental borate provinces are recognized at a global scale. They are located in Anatolia (Turkey), California (USA), Central Andes (South America) and Tibet (Central Asia). The origin of borate deposits is related to Cenozoic volcanism, thermal spring activity, closed basins and arid climate. Borax is the major commercial source of boron, with major supplies coming from Turkey. Colemanite is the main calcium borate and large scale production is restricted to Turkey. Main borax (tincal) deposits are present in Anatolia (Kirka), California (Boron), and two in the Andes (Tincalayu and Loma Blanca). Colemanite deposits with/without probertite and hydroboracite are present in west Anatolia, Death Valley, California, and Sijes (Argentina). Quaternary borates are present in salars (Andes) and playa-lakes and salt pans (USA and Tibet). The Karapinar playa-lake is located in central Turkey. The formation of borate deposits consisting of a sodium– and calcium–borate hydrates group associated with playa-lake sediments and explosive volcanic activity. Some conditions are essential for the formation of economically viable borate deposits, playa-lake volcano-sedimentary sequences: formation of playa-lake environment; concentration of boron in the playa lake, sourced from andesitic to rhyolitic volcanics, direct ash fall into the basin, or hydrothermal solutions along faults; thermal springs near areas of volcanic activity; arid to semi-arid climatic conditions; and lake water with a pH of between 8.5 and 11. A large number of minerals contain boric oxide, but the three that are most important from a worldwide commercial standpoint are borax, ulexite, and colemanite, which are produced in a limited number of countries. Turkey has the largest borax, ulexite and colemanite reserves in the world and all the world’s countries are dependent upon the colemanite and ulexite reserves of Turkey. The main borate districts are located in Bigadic, Kestelek, Sultancayir, Emet, Kirka and Gocenoluk areas. Most of the world’s commercial borate deposits are mined by open pit methods. Boric acid is one of the final products produced from most of the processes. Further research on the mineralogy and chemistry of borate minerals and associated minerals will the production and utilization of borate end-products. Many modern industries need industrial borate minerals, and many individuals use their products. Therefore, borates and associated products are critical for the sustainable development of the world.