The mounds are amygdaloidal
in cross section, 11-20 mm long, up to 9 mm high and only slightly wider than the even ridge.
Hematite is found in amygdaloidal
cavities as druses of silvery black microscopic crystals on datolite, prehnite, albite, calcite, heulandite and stilbite.
The volcanics are amygdaloidal
in nature and exhibit porphyritic, cumulophyric and intergranular textures.
Some mineralization also occurs in the basalt above this horizon, in veins that transect the flows and in vertically bulging, dome-like regions of amygdaloidal
basalt, referred to as diapirs by Laskowich and Puffer (1990).
In 1982, dachiardite-Na was found in the alcove on the upper level in what appear to be amygdaloidal
basaltic sills (A.
This sample is amygdaloidal
and fine grained, with about 10-15% mesostasis that is intergranular to matrix plagioclase and clinopyroxene (Fig.
The drill hole intersected Bowser sediments to a depth of 47 metres, and intercalated pyritic mudstone and amygdaloidal
basalt to 144 metres.
The amethyst crystals occur in small to large clefts, or cleft-systems, which are similar to Alpine clefts and fundamentally different from geodes or amygdaloidal
cavities which are the result of gas bubbles in lava.
Most basalt in the area is massive, but considerable amounts are amygdaloidal
Recently, PDUS re-logged the cuttings in PRH0508 and despite an initial determination that the hole intersected lower plate, amygdaloidal
textures in the cuttings suggest volcanic greenstone is present in several intervals down to the bottom of the hole.
The Eastport Formation in New Brunswick comprises amygdaloidal
mafic flows and agglomerate, massive to flow-banded felsic flows, welded and non-welded lapilli tuff, pisolitic tuff, peperitic breccia, and grey to maroon sandstone and conglomerate totalling ~4000 m (Hay 1967; Pickerill and Pajari 1976; Pickerill et al.
The upper 5 to 8 meters of this first flow is amygdaloidal
and contains the majority of the best specimen-quality minerals.