A-myg'da-loid, n.

[Gr. ἀμύγδαλον, almond, and εἶδος, form; Ger. mandelstein, almond-stone.] (Min.) A variety of trap or basaltic rock, containing small cavities, occupied, wholly or in part, by nodules or geodes of different minerals, particularly agates, quartz, calcareous spar, and the zeolites. When the imbedded minerals are detached, it is porous, like lava. Dana.