Basalt, sodium

Sodium in Basalt and Lava. Nicholson s Journal for October, 1798, contains an account of the first discovery of sodium in a stony mineral. Early in August of that year Dr. Robert Kennedy announced to tire Royal... 

Society of Edinburgh that lie had discovered soda in several varieties of Scottish whinstone and m lava from Mt, Aetna (25). He used the term whinstone to include basalt, trap, and certain kinds of porphyry, wacke, and other argillaceous stones. When he analyzed a specimen which had been broken from one of the famous basaltic columns of Staffa, he found that the sum of the earths, silica, and iron never amounted to more than 94 per cent. Suspecting the presence of an alkali, he heated the pulverized mineral with pure sulfuric acid and extracted a salt which he identified as sodium sulfate (25). He proved, moreover, that the sodium compounds had not been dissolved from his glass apparatus. Dr. Kennedy also found 4 per cent of soda in a specimen of lava brought to him by Sir James Hall and Dr. James Home from the famous current of Mt. Aetna which in 1669 had destroyed part of the town of Catania. He published these analyses in 1800 in Nicholsons Journal (25). 

A large variety of zeolite species crystallize from volcanic glasses under weathering conditions and several can be associated in the same sample. The process seems most pronounced for acid eruptive rocks (Hay, 1963 Iijima and Harada, 1969 Harada, t al., 1967) but does occur in basalts also (Hay and Iijima, 1970). In some African soil profiles, zeolites (analcite) are found to develop at the expense of montmorillonite and sodium carbonate their appearance is apparently a function of local drainage. They grow in more stagnant situations at the expense of montmorillonite (Frankart and Herbillon, 1970). 

Figure 2. Sodium released to the aqueous solution during the dissolution of powders from three rock types. ( ), Eleana shale (UE-17e) (0), quartz mon-zonite (U15e-7) ( ), umtanum basalt (DC 3-3600).

An auxiliary experiment, performed at 90°C with ground-water and a column of crushed basalt chips and with a basalt surface area to groundwater volume ratio equivalent to that of the analog basalt fissure (2 x 10 cm" ), has elucidated this phenomenon Data from this experiment, which are presented in Figure 3, show that the sodium-ion concentration of the ground-water does not decrease gradually from its initial value of... 

In the presence of high concentrations of both sulfate and fluoride, the speciation results are somewhat more difficult to interpret. Generally, the effect of fluoride predominates over that of sulfate, but not always. In deionized water containing added fluoride and sulfate to equal the concentrations of these two anions in basalt and shale ground waters, respectively, essentially all the plutonium was soluble—similar to its behavior in deionized water containing only added fluoride. Also, addition of sodium sulfate to basalt ground water to increase its concentration to that of shale ground water had no appreciable effect on plutonium solubility. 

Atherton M. P. and Petford N. (1993) Generation of sodium-rich magmas from newly underplated basaltic crust. Nature 362, 144-146. 

Table 3 lists examples of more than a dozen different chemical types of river water. Although Ca and HCO j" are generally dominant, Mg dominance over Ca + can be found in rivers draining various lithologies such as basalt, peridotite, serpentinite, dolomite, coal, or where hydro-thermal influence is important (Semliki). Sodium may dominate in sandstone basins, in black shales (Powder, Redwater in Montana), in evaporitic sedimentary basins (Salt), in evaporated basins (Saoura), and where hydrothermal and volcanic influence is important (Semliki, Tokaanu). rarely exceeds 4% of cations, except in some clayey sands, mica schists, and trachyandesite it exceeds 15% in extremely dilute waters of Central Amazonia and in highly mineralized waters of rift lake outlets (Semliki, Ruzizi). 

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