from The American Heritage® Dictionary of the English Language, 4th Edition
- n. An amorphous, translucent, variously colored mineral, essentially hydrous aluminum silicate.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An amorphous hydrous aluminium silicate clay mineral.
from The Century Dictionary and Cyclopedia
- n. A mineral of a pale-blue, and sometimes of a green or brown, color.
Volcanic deposits have a unique process of weathering that causes the accumulation of allophane and oxides of iron and aluminum in developing soils.