The mineralogy of ten trihydrate bauxites and their leached residues from bomb digestion tests at 140, 180 and 2400C was investigated and the resultscorrelated with analytical data. It is shown that increased recovery of alumina at high temperatures is due to. the dehydroxylation of goethiterather than the presence of alumina monohydrates. The effects of aluminous goethite -on the interpretation of "available alumina"._x000D_
results-and normative analysis are discussed and it is concluded that,'cautionmust be exercised in interpreting the results of bomb digestion tests in terms of alumina hvdrates.