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Webster 1828 Edition

Noun.

[Gr. other and to appear.]

A mineral of a blue, and sometimes of a green or brown color, which occurs massive, or in imitative shapes. It gelatinizes in acids.

Allophane is a variety of clay, occurring in amorphous, botryoidal or reniform masses.

allophane ‎(countable and uncountable, plural allophanes)

an amorphous hydrous aluminium silicate clay mineral