amygdule

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amygdule

[ə′mig‚dyül]
(geology)
A mineral filling formed in vesicles (cavities) of lava flows; it may be chalcedony, opal, calcite, chlorite, or prehnite.
An agate pebble.
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References in periodicals archive ?
These appear to be amygdules, suggesting that the dyke may be a subvolcanic (shallow) intrusion.
However, its position in the succession of other amygdule minerals is uncertain.
Near the top of this unit is a zone of brecciated scoria, slag-like basalt containing numerous amygdules, all less than 2.
It contains numerous small pipe amygdules lined or totally filled with albite and calcite.
Prehnite pseudomorphs after glauberite are widespread within the diapiric amygdules of the first and second flows.
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.
Locally, it contains mineral-filled amygdules less than 1 cm in diameter.
The amygdules are generally filled with white minerals, and give the dark, brownish gray rock a spotted appearance.
The mineral was found as a transparent, yellow to orange crystalline filling in amygdules 2-5 mm across, in a dark sill rock with a spotted appearance (A.
Although amygdules are distributed throughout the dike, those containing voggite are localized within a few centimeters of the contact between the dike and the phonolite sill.
The mineralogy of the Caledonia mine is typical of the area mines and consists of quartz, calcite, epidote and red K-feldspar that fill amygdules and cement rock fragments.