Hydrobasaluminite and basaluminite are found in sedimentary rocks in southeastern Kansas. Hydrobasaluminite is closely associated with gypsum and iron oxides and occurs locally above a Middle Pennsylvanian coal. Basaluminite, a dehydrated form of hydrobasaluminite, is found only as debris on dry slopes. X-ray studies indicate no intermediate stages between hydrobasaluminite and basaluminite.

Basaluminite changes to metabasaluminite between 75°C and 330°C, but samples heated below 200°C partly or completely rehydrated upon cooling. Part of the material becomes amorphous if heated above 280°C. Two intermediate stages of poorly crystalline material are developed at temperatures between 340°C and 850°C. Above 850°C, samples gradually change to α-alumina.

Single crystallites of basaluminite have well-defined rhombic plates. Sides of the plates are about one micron in length with thicknesses of 0.05 micron. The chemical composition of basaluminite is approximately 2Al2O3·SO3·10H2O; composition of hydrobasaluminite is questionable.

Differential thermal analyses of hydrobasaluminite show endothermic peaks at 155°C, 220°C, 355°C, 890°C, and 940°C. Basaluminite has endothermic peaks at 125°C, 170°C, 220°C, 355°C, and 940°C. Infrared spectra of basaluminite in the range 400 to 4000 cm-1 show typical sulfate absorption bands from 580 to 690 cm-1 and 1050 to 1200 cm-1. X-ray diffraction data indicate basaluminite samples from Kansas, England, and Tennessee are identical.

Field evidence suggests that the formation of hydrobasaluminite is related to weathering, local structure, topography, and mineral composition of associated rocks. Local accumulations of alkalic and acidic solutions caused precipitation of hydrobasaluminite and associated gypsum and iron oxides.

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