amygdalen.
Geol.
A vesicle in a lava filled with secondary minerals.
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amygdale1897
1897 A. Geikie Anc. Volcanoes Great Brit. I. iii. 15 As the kernels thus produced are frequently flattened or almond-shaped (amygdales).., the rocks containing them are said to be amygdaloidal.
1916 Q. Jrnl. Geol. Soc. 72 232 The amygdales are occupied by agate, jasper, and quartz, and by a variety of zeolites.
1944 A. Holmes Princ. Physical Geol. v. 49 The filled ‘bubbles’ sometimes look like almonds, and so the name amygdale is given to them.
1990 C. Pellant Rocks, Minerals & Fossils 23/1 The amygdales are both round and elongated and contain calcite, the rhombic cleavage of which is visible.
This entry has not yet been fully updated (first published 1997; most recently modified version published online November 2010).
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