amygdule


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a·myg·dule

 (ə-mĭg′dyo͞ol)
n.
A small gas bubble in igneous, especially volcanic, rock filled with secondary minerals such as zeolite, calcite, or quartz.
[Latin amygdala, almond (from its shape); see amygdala + (nod)ule.]
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.
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References in periodicals archive ?
Natrolite is an extremely rare zeolite at the Fanwood quarry; specimens were discovered on one occasion as jumbles of acicular crystals, no longer than 1 cm, on prehnite in a diapiric amygdule. The crystals are white and exhibit the classic elongated orthorhombic prism with pyramidal terminations.
The principal secondary mineralization is found in the amygdules: gas pockets located in the upper parts of the first, second and third basalt flows and in the adjacent 20 cm of the overlying flows.
The Fanwood quarry: Somerset County New Jersey
However, its position in the succession of other amygdule minerals is uncertain.
Two samples of trachyandesite representing two principal facies: DO-1-1 (fresh material without amygdales) and DO-1-2 (zeolitized sample with numerous amygdules), were taken for petrographic and geochemical studies.
Zeolite-bearing trachyandesite from Dobranka, Ceske stredohori Mts.: petrography, geochemistry and amygdale mineralogy
Locally, it contains mineral-filled amygdules less than 1 cm in diameter.
Famous mineral localities: the Francon quarry, Montreal, Quebec

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