| Unlike imogolite, the morphology of allophane varies from fine, rounded particles through ring-shaped particles to irregular aggregates. |
| Allophane structures are characterized by the dominance of Si-O-Al Si-O-Al Si-O-Al majority of aluminum atoms are tetrahedrally coordinated. |
| However, orthopyroxene, olivine and mangnetite were also detected in contaminated soils including allophane and quartz. |
| In general, the SiO2 Al2O3 ratio of allophane is higher than that of imogolite. |
| A good example is a comparison of the PI of montmorillonite with that of allophane or palygorskite. |
| The highly soluble and aluminous bytownite favored the formation of allophane. |
