Solubility of microcline, muscovite and quartz and the speciation of Al in supercritical H[sub 2]O

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5690784

Walther, J V ^[1]; Woodland, A B ^[2]

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1. Northwestern Univ., Evanston, IL (United States). Dept. of Geological Sciences
2. Univ. Bayrueth (Germany). Bayerisches Geoinstitut

The concentrations of K, Na, Al and Si in an aqueous fluid in equilibrium with natural microcline, muscovite, and quartz have been measured between 400 and 600 C at 2 kbar with an extraction-quench apparatus. Si is the dominant solute in solution and its concentration is similar to those reported for quartz solubility in pure H[sub 2]O; increasing from 0.05 m at 400 C to 0.12 at 600 C. The small amount of Na in the microcline and muscovite was rapidly leached from the mineral surface so that the initial concentration of Na equaled 0.002 m but decreased as pure H[sub 2]O was injected into the charge volume. Log molalities of K in equilibrium with the mineral assemblage are between [minus]3.0 and [minus]2.7. These are less than in equilibrium with albite-paragonite-quartz under similar conditions. The calculated solution compositions are somewhat basic and Al(OH)[sub 4][sup [minus]] is determined to be the dominant al species in solution. These calculations suggest that Al(OH)[sub 4][sup [minus]] is also the dominant species in equilibrium with corundum in pure H[sub 2]O at these conditions although Al(OH)[sub 3][sup 0] is also important. The standard molal Gibbs free energy of formation of Al(OH)[sub 4][sup [minus]] was calculated. No evidence exists for the formation of significant concentrations of alkali-Al complexes despite the fact that Al molalities in solution are an order of magnitude greater than in corundum solubility experiments. The tetrahedral coordination of Al with OH[sup [minus]] appears to be the most stable complex of Al at near neutral to somewhat basic conditions at 2 kbar between 400 and 600 C.

• OSTI ID: 5690784
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
152003* -- Geothermal Data & Theory-- Rock-Water-Gas Interactions
ALKALI METALS
ALUMINIUM
ALUMINIUM COMPOUNDS
ELEMENTS
ENERGY
EQUILIBRIUM
FELDSPARS
FLUIDS
FORMATION FREE ENERGY
FREE ENERGY
GASES
METALS
MICA
MICROCLINE
MINERALS
MUSCOVITE
OXIDE MINERALS
PHYSICAL PROPERTIES
POTASSIUM
QUARTZ
ROCK-FLUID INTERACTIONS
SEMIMETALS
SILICATE MINERALS
SILICON
SODIUM
SOLUBILITY
SUPERCRITICAL STATE
THERMODYNAMIC PROPERTIES
VAPORS
WATER VAPOR