In contrast to most northern New Jersey quarries, prehnite is uncommon at the Braen quarry, and its distribution is limited to the amygdaloidal
and scoriaceous basalt overlying the pillow basalt complex; it is also found in the openings in diapirs.
This sample is amygdaloidal
and fine grained, with about 10-15% mesostasis that is intergranular to matrix plagioclase and clinopyroxene (Fig.
basalt flows have amygdale fillings principally of celadonite and silica minerals, with minor amounts of zeolite.
(or Plate) 531, a depiction of toadstone, an amygdaloidal
basalt, from British Mineralogy.
The top few metres are often amygdaloidal
and mafic pegmatites locally occur with felsic layers ([less than or equal to]2-3 cm).
Basaltic fragments are abundant in the coarse lithic tuff at Gorhams Bluff where they underlie an amygdaloidal
basalt flow near the top of the section.
Comprising from 10 to 20% of the rock, fragments (1-15 cm in size) include greyish pink aphyric and porphyritic felsic volcanic rocks, dark grey mudstone, greyish green amygdaloidal mafic volcanic rocks, and rare clasts of massive sulphides.
The breccia contains sparse to abundant, light grey, fine-grained, angular, amygdaloidal, porphyritic to aphyric andesite fragments from 1 to 20 cm in size set in a very fine-grained, feldspathic matrix (Fig.
The Long Pond Bay Formation is defined to include a sequence of oxidized, coarsely amygdaloidal
mafic volcanic flows and interbedded arkosic grit on Wood Island, and a succession of hyaloclastic mafic flows, laminated siltstone and turbiditic sandstone exposed on the southeast coast of Grand Manan Island, itself.
Lavas are commonly amygdaloidal and/or microporphyritic with phenocrysts of feldspar and, more rarely, pyroxene or quartz, set in a glassy to microcrystalline groundmass.
Most of the samples are amygdaloidal and microporphyritic with glassy to microcrystalline groundmass.