a. and sb. [f. Gr. ἀμυγδάλη almond + -OID. Cf. mod.Fr. amydaloïde.]
A. adj. Almond-shaped; having almond-shaped nodules.
1836. Todd, Cycl. Anat. & Phys., I. 583/1. The amygdaloid lobe.
1852. T. Ross, Humboldt’s Trav., II. xvii. 79. The clay which separates these amygdaloid concretions.
1858. Beveridge, Hist. Ind., I. Introd. 7. Basaltic trap … globular, tabular, porphyritic, and amygdaloid.
1870. Hooker, Stud. Flora, 323. Sea Buckthorn … embryo amygdaloid.
B. sb. Geol. An igneous rock, usually trappean, containing almond-shaped nodules or geodes of some mineral, as agate, chalcedony, or calc spar.
1791. Beddoes, in Phil. Trans., LXXXI. 69. The crystals often occurring in the cavities of the amygdaloides rocks.
1802. Playfair, Illust. Hutton. The., 67. The common basalt … and the amygdaloid, are comprehended under the name of whin.
1833. Lyell, Princ. Geol., III. 361. Converting porous lava into amygdaloids.
1847. Tennyson, Princess, III. 343. Chattering stony names Of shale and hornblende, rag and trap and tuff, Amygdaloid and trachyte.
1876. Page, Advd. Text-bk. Geol., v. 105. Amygdaloids having their vesicular cavities filled with agate, carnelian, calc-spar, &c.
