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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.

Pertaining to, or having the nature of, the rock amygdaloid.

d also dragon root. -- Green earth (Min.), a variety of glauconite, found in cavities in amygdaloid and other eruptive rock, and used as a pigment by artists; -- called also mountain green. -- Green ebony. (a) A south American tree (Jacaranda ovalifolia), having a greenish wood, used for rulers, turned and inlaid wor…

A mineral of the Zeolite family, often occurring in amygdaloid, in foliated masses, and also in monoclinic crystals with pearly luster on the cleavage face. It is a hydrous silicate of alumina and lime.

Amygdaloid.

Scotch pebble, varieties of quartz, as agate, chalcedony, etc., obtained from cavities in amygdaloid.

avy igneous rocks, including especially the feldspathic- augitic rocks, basalt, dolerite, amygdaloid, etc., but including also some kinds of diorite. Called also trap rock. Trap tufa, Trap tuff, a kind of fragmental rock made up of fragments and earthy materials from trap rocks.

onite, heulandite, and others. These species occur of secondary origin in the cavities of amygdaloid, basalt, and lava, also, less frequently, in granite and gneiss. So called because many of these species intumesce before the blowpipe. Needle zeolite, needlestone; natrolite.