Amygdaloid n. (Min.) A variety of trap or basaltic rock, containing small cavities, occupied, wholly or in part, by nodules or geodes of different minerals, esp. agates, quartz, calcite, and the zeolites. When the imbedded minerals are detached or removed by decomposition, it is porous, like lava.
adjective
Amygdaloidal, Amygdaloid adj.
1.
Almond-shaped.
2.
Pertaining to, or having the nature of, the rock amygdaloid.
... sedimentary strata similar to those of former ages. If I may be allowed to borrow a striking illustration from the geological relations by which the physiognomy of a country is determined, I would say that domes of trachyte, cones of basalt, lava streams ('coules')of amygdaloid with elongated and parallel pores, and white deposits of pumice, intermixed with black scoriae, animate the scenery by the associations of the past which they awaken, acting upon the imagination of the enlightened observer like ... — COSMOS: A Sketch of the Physical Description of the Universe, Vol. 1 • Alexander von Humboldt
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