It can be assumed that a portion of the rigid amorphous chains, trapped in the polymer-particle interphase, is
devitrified above a critical temperature, increasing the nucleation rate.
The groundmass is largely composed of
devitrified glass with phenocrysts of feldspar, clinopyroxene, and quartz, and rare ilmenite, hematite, sphalerite, and galena.
The only factor detrimental to that hypothesis is an indication that felsic volcanic rocks of the Torres Strait Volcanics are rather widely
devitrified (Willmott et al.
Variable alteration; in some, the groundmass has been
devitrified. Elongate to equant.
In this locality, volcanic ash was deposited over a large area and subsequently
devitrified in both shallow marine and lacustrine environments (Roberson, 1964).
Waste ceramics -
devitrified glass, glass cullet, ceramic ware, and waste from cast iron enameling - have been considered.
It consists of plagioclase brown to orange
devitrified glass and ilmenite.
Middle right: Porphyritic dolerite comprising plagioclase (An50), pinkish augite with opaque oxide along fractures,
devitrified glass (dark patches), and secondary minerals.
The sample contains approximately equal proportions of broken and fractured quartz and potassium feldspar phenocrysts, and subordinate plagioclase crystals in a matrix of rounded,
devitrified rhyolite fragments and crystal debris.
Their principal constituents include titaniferous augite, aegirine augite, hornblende, phlogopite, plagioclase (An 37-88),
devitrified volcnic glass, noseam and olivine.
The other mafic sample, 30, is a hyaloclastite composed of angular, formerly glassy, fragments,
devitrified to microlite around coarse vesicles.
In some thin sections the rocks have olivine as phenocryst, opaque and
devitrified glass in the groundmass (Fig.
Volcanic Glass: The volcanic glass is commonly
devitrified and has brown colour, which generally occurs in groundmass and as fillings in vesicles.
