In a paragraph in the textbook "When CSIRO scientists were called in to investigate, they discovered that the cause was the oxidation of iron pyrites in these area, much of which had been exposed as a result of draining swamps for grazing cattle and the use of floodgates to drain cane fields. This released sulfuric acid, which in turn mobilised the aluminium ions in the clays. These ions are also acidic." How can aluminium ions be acidic? Is it saying Al(3+) is an acid?