Konyaite in Salt Efflorescence from a Tertiary Marine Deposit near Geelong, Victoria, Australia

Abstract

Konyaite [Na2Mg(SO4)2·5H2O] was identified for the first time in Australia in salt efflorescences from a Tertiary marine deposit below exposed basalt flows at a quarry near Geelong, Victoria. Other soluble salts in the efflorescence were epsomite (MgSO4·7H2O), gypsum (CaSO4·2H2O), and halite (NaCl). Heating at 110°C converted the konyaite to a mixture of bloedite [Na2Mg(SO4)2·4H2O], loeweite [Na4Mg2(SO4)4·5H2O], and thenardite (Na2SO4). Recrystallization at 23°C of the efflorescence dissolved in varying amounts of water indicated that epsomite and thenardite form from dilute solutions, whereas increasing amounts of konyaite recrystallize from the more concentrated solutions under faster evaporative conditions. The salts are transported to the basalt quarry site in river seepage or ground water from the neighboring marine deposits and are left on the exposed surfaces by evaporation.

Effects of Salt Mineralogy on Dust Emissions, Salton Sea, California

“…Anhydrite is generally not very common in the southwestern United States because its stability requires high temperatures and low relative humidities. Konyaite is also generally thought to be relatively unstable (Van Doesburg et al, 1982;Shayan and Lancucki, 1984;Kohut and Dudas, 1993) and has not been found in this region. Thus, the most common sets of hydrous/anhydrous minerals in the southwestern United States are thenardite/mirabilite, glauberite/eugsterite, and gypsum/bassanite (± anhydrite).…”

The crystal structure and hydrogen bonding of synthetic konyaite, Na2Mg(SO4)2{middle dot}5H2O

“…Little is * E-mail: leduc@geoladm.geol.queensu.ca known about the field of stability of konyaite; Keller et al (1986a) reported having found konyaite between 6.3 and 37.9 °C, but no relative humidity constraints were provided. They suggested however, as Shayan and Lancucki (1984) did before them, that konyaite typically forms in nature and dehydrates to form blödite, and that although direct formation of blödite is possible, the required conditions for its formation do not occur as frequently as those required for konyaite. Its status as a metastable phase (van Doesburg et al 1982;Friedel 1976) has also been questioned by Timpson et al (1986), although its soluble nature and sensitivity to relative humidity changes make it subject to remobilization into the local watershed.…”

“…the Na 2 O-MgO-SO 4 -H 2 O system (Shayan and Lancucki 1984). The mineral appears to form in disequilibrium with its parent saline solution, and to alter to blödite within a matter of days at room temperature, if the crystals stay in contact with the solution (Friedel 1976).…”

“…Numerous studies have, since then, identified konyaite as an important phase in saline soils (Shayan and Lancucki 1984;Timpson et al 1986;Zielinski et al 2001). Konyaite was also found to be the most common phase in mineral assemblages sampled in North Dakota by Keller et al (1986a).…”

Hydrothermal Alterations of Hisingerite Material from a Basalt Quarry Near Geelong, Victoria, Australia

“…The fact that goethite, rather than hematite, coexists with nontronite further indicates a low-temperature alteration. Shayan and Lancucki (1984) found that the ground water moving through the green basalt at Geelong had the composition (mmole/liter) of Na (88.8), Mg (8.5), Ca (0.85), Sr (0.01), CO32-(1.2), HCO3-(11.2), SO42-(3.94), and C1-(86.0) and a pH of 8.34. This composition may have been reached by river water moving through the surrounding Tertiary marine deposits before it intersected the basalt flow.…”