Winter crystallization of mirabilite salt. Solubility calculations show the lake naturally produces 500,000 tons annually, mined since the 1930s for detergent manufacturing.
A chemical factory powered by winter
Alakol Lake, a vast saline body of water in a steppe basin of eastern Kazakhstan, operates as a massive, natural chemical plant driven by seasonal temperature changes. The lake's water has high levels of sodium sulfate. The solubility of this compound in water has a peculiar property: it increases dramatically with temperature up to 32.384 °C, then remains almost constant. This specific temperature is the transition point where the hydrated form of the salt becomes unstable.
During the hot summer months, water evaporates and the concentration of sodium sulfate in the lake brine increases. As winter approaches and the water temperature drops below this 32.384 °C threshold, the water becomes supersaturated. The dissolved salt can no longer stay in solution and begins to precipitate out, forming vast deposits of a mineral called mirabilite, or Glauber's salt. This hydrated sodium sulfate (Na₂SO₄·10H₂O) crystallizes on the lakebed in a process known as cryogenic or cooling crystallization. This natural, temperature-driven separation process makes the mineral available for harvesting.
From lakebed to laundry
The industrial collection of Alakol's mirabilite began in the 1930s. The process takes advantage of the cold, shallow conditions of the lake in winter. Once the mirabilite has crystallized, it is harvested from the lakebed. The raw Glauber's salt is then processed to remove the water of crystallization, converting it into anhydrous sodium sulfate (Na₂SO₄), a fine white powder also known as thenardite. This final product is an important component in manufacturing powdered laundry detergents, where it is a filler to standardize the product's volume.
The scale of this natural production is immense, with estimates suggesting the lake precipitates around 500,000 tons of mirabilite each year. Beyond detergents, the sodium sulfate sourced from the lake is used in the manufacturing of glass, paper, and textiles, where it helps ensure dyes are applied evenly. The lake is one of the world's significant sources of natural sodium sulfate, shows a unique combination of geochemistry and climate. The Alakol-Sasykkol lake system is also recognized as a UNESCO Biosphere Reserve and a Ramsar Wetland of International Importance, primarily for its importance as a stopover on the Central Asian–Indian bird migration route.
💡Fun Facts
Mirabilite gets its other name, Glauber's salt, from the 17th-century German-Dutch chemist Johann Rudolf Glauber, who first synthesized it and called it "sal mirabilis" or "wonderful salt".
In dry air, mirabilite is unstable and quickly dehydrates, crumbling into a white powder of its anhydrous form, thenardite.
The precise temperature at which hydrated sodium sulfate melts (32.384 °C) is so reliable that it is used as a standard for calibrating thermometers.
Alakol means "Motley Lake" in the Kazakh language, a name that reflects how its water changes color from deep blue to green depending on the weather and light.
The industrial harvesting areas are not open to the public. The general shoreline of the lake is accessible year-round.
Admission
Free to access the lake's public beaches and shores.
Accessibility
The terrain around the lake is primarily undeveloped steppe and pebble beaches. Paved roads lead to the main resort areas, but accessing more remote parts of the shoreline may require an off-road vehicle.
Alakol Lake sodium sulfate harvestingAlmaty Region, Kazakhstan