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An amorphous, translucent, variously colored mineral, essentially hydrous aluminum silicate.
[From Greek allophanēs, appearing otherwise : allos, other; see allo- + phainesthai, phan-, to appear, passive of phainein, to show; see bhā- in Indo-European roots.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
(Minerals) a variously coloured amorphous mineral consisting of hydrated aluminium silicate and occurring in cracks in some sedimentary rocks
[C19: from Greek allophanēs appearing differently, from allo- + phainesthai to appear]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
a clay mineral, an amorphous hydrous silicate of aluminum, occurring in blue, green, or yellow, resinous to earthy masses.
[1835–45; < Greek allophanḗs appearing otherwie]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.