‖ mandelsteinGeol.|ˈmandəlʃtaɪn| Also anglicized mandelstone. [G., f.mandel almond + stein stone.] = amygdaloid n. 1799Kirwan Geol.Ess. 202 Mandelstein (or Amygdaloid).1852Th. Ross Humboldt's Trav. I. i. 35 The porous basalt which passes into mandelstein.