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1. A rock formation that resembles beads, found in glassy igneous rocks.
2. Archaic A pearl.
[Ultimately from Greek margarītēs, pearl, perhaps of Iranian origin; perhaps akin to Avestan mərəγa-, bird (since the two valves of some pearl-bearing bivalves resemble a pair of bird wings when spread open) .]
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.
1. (Minerals) a pink pearly micaceous mineral consisting of hydrated calcium aluminium silicate. Formula: CaAl4Si2O10(OH)2
2. (Geological Science) an aggregate of minute beadlike masses occurring in some glassy igneous rocks
[C19: via German from Greek margaron pearl]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
Archaic. a pearl.
[before 1000; Middle English, Old English: pearl < Latin margarīta < Greek margaritēs]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.