Diaspore properties

The possible content of hydrated alumina and iron. Hydrated alumina minerals like gibbsite [14762-49-3] Al(OH)2, boehmite [1318-23-6] AlOOH, and diaspore [14457-84-2] AlOOH, occur ia bauxitic clays. Bauxites grade chemically iato hydrated fermgiaous and manganiferous laterites. Hence, finely divided M2O2, usually hydrated, may be a significant constituent of a clay where M may be A1 or Fe. Hydrated colloidal s ica may play a role ia the sHppery and sticky properties of certain clays. 

Diaryl pyrrolopyrroles (DPPs), 79 441-443 commercial, 79 443t Diarylthallium(III) derivatives, 24 634 Diaspore, 2 345t, 347, 426 classification, 2 422 decomposition sequence, 2 392, 421 mineralogical and structural properties of, 2 423t... 

Mineralogical properties of boehmite, 2 423t of diaspore, 2 423t of gibbsite, 2 423t Mineralogy, 16 601-603 Mineral oil... 

Calcination of Diaspore at 500°C Properties a-form, specific surface area given in Table 3.169 [1084]. 

The solubilities of gibbsite, boehmite and diaspore in alkaline solutions between 20 and 350°C are evaluated and their thermodynamic properties reconciled. The thermodynamic properties of the aluminate ion, Al(OH)4, are derived over the same temperature range and compared with predictions based on the revised Helgeson-Kirkham-Flowers equation of state. Preliminary thermodynamic properties of bayerite and AGf°298 for nordstrandite are also derived from solubility data in alkaline solutions. Log Kg4 values for gibbsite, bayerite, boehmite and diaspore between 0 and 350°C, and thermodynamic data for A1(0H)4 or AIO2, re tabulated for use in distribution-of-species computer codes. 

Table I. Summary of thermodynamic properties of gibbsite, boehmite, diaspore, and corundum...

The Aluminate Ion, Al(OH)4. Calculation of AG ° or log K° of the aluminate ion from gibbsite, boehmite and diaspore in alkaline solutions using equations (1) or (2) requires the corresponding standard state partial molal properties of the hydroxyl ion, OH . These may be determined from the dissociation constant for water, if it is accurately known over the range of temperatures and pressures investigated. The experimental measurements of diaspore solubility, reported here, extend to 350°C on the aqueous phase saturation surface, but experimental determinations of by Sweeton et al. ( ) attain only... 

Another important thermal property dealt with in Sec. 13.6 is thermal conductivity. It is the low thermal conductivity of ceramics, together with their chemical inertness and oxidation resistance, that renders them as a class of materials uniquely qualified to play an extremely demanding and critical role during metal smelting and refining. Many ceramics such as diaspore, alumina, fosterite, and periclase are used for the fabrication of high-temperature insulative firebrick without which the refining of some metals would be impossible. 

A relatively new source of sapphires is Madagascar. Stones from this occurrence have partly overlapping properties to those from Sri Lanka and Kashmir [23], In addition, several mineral inclusions such as apatite, zircon, and calcite, three-phase inclusions consisting of a liquid and gaseous phase of CO2 and diaspore as the solid phase (Fig. 9) could be identified. Three-phase inclusions with such a composition have so far only been observed in sapphires from Sri Lanka, thus ruling out Kashmir as possible source. 

Apps, J.A., Neil, J.M. and Jun, C.H. (1989) Thermochemical Properties of Gibbsite, Bayerite, Boehmite, Diaspore and the Aluminate Ion Between 0 and 350 °C. Lawrence Berkeley National Laboratory Report 21482. 

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