Century Dictionary and Cyclopedia
- Same as amygdaloid; specifically, in geology, having a cellular or vesicular structure: said of lava, whether of modern or ancient origin, in which spherical or almond-shaped (whence the name) cavities were formed by the expansion of steam contained in the rocks at the time of its consolidation, and which have later become filled with various minerals, especially quartz, calcite, or the zeolites. The rock having this character is called an amygdaloid, and the cavities themselves, as thus filled by the percolation of heated water through the body of the rock, are called amygdules.
- adj. shaped like an almond
“The part of the western shore where the land is highest shelters a small bay which might be made a tolerable harbour by means of two piers or quays erected on reefs of a kind of rock apparently very favourable for the purpose, namely amygdaloidal trap in rounded boulders.”
“This hill consisted of amygdaloidal trap in nodules, the crevices being filled with crystals of sulphate of lime, and there were many round balls of ironstone, like marbles or round shot, strewed about.”
“I ascended one, and found it was capped with trap rock in amygdaloidal nodules.”
“It is a common product of alteration in igneous rocks, and frequently occurs as well-developed crystals in association with zeolites lining the amygdaloidal cavities of basaltic and other rocks.”
“The openings in rocks consist of joints and many other fractures, small spaces between the grains of rocks (pore space), and amygdaloidal and other openings characteristic of surface volcanic rocks.”
“The ore bodies have the form of long sheets parallel to the bedding, the copper and associated minerals filling amygdaloidal openings and small fissures in the flows, and replacing conglomeratic sediments which lie between the flows.”
“The Fountain of Saint Vulcan, anti-blepharous and amygdaloidal, was charged with such potent minerals that a single spoonful produced a diarrhoea more distressing to witness than cholera.”
“The summit of Machacha is composed of a dark igneous rock, apparently a sort of amygdaloidal trap, with white and greenish calcareous crystals scattered through it.”
“They are generally trap-rock, embracing the varieties of gray, porphyritic, hornblendic, sienitic, and amygdaloidal trap, and appear to have had no labor expended upon them except the chiseling of a groove around the middle for the purpose of attaching a withe to serve as a handle.”
“The rocks in its bed are limestone, but a great bluff cliff of sandy conglomerate (strike east-south-east and dip south-south-west 70 degrees), several hundred feet high, rises on the east bank close above the village, above which occurs amygdaloidal basalt.”
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