Vitrophyre

vitrophyre

[′vi·trə‚fīr]
(petrology)
Any porphyritic igneous rock whose groundmass is glassy. Also known as glass porphyry.

Vitrophyre

 

(from Latin vitrum, glass, and Greek porphyra, purple, crimson, dark-red), a general name for effusive rock consisting almost entirely of volcanic glass with a small quantity of mineral phenocrysts. Usually this is quartz or orthoclase porphyry with a glassy or cryptocrystalline base. The term “vitrophyre” is also used to refer to the structure of certain glassy rocks (so-called vitrophyric structure) containing a certain quantity of phenocrysts or microlites (for example, vitrophyric basalt, or vitrobasalt, and vitroandesite).

References in periodicals archive ?
We studied 35 slabs of peralkaline rocks: 22 samples of vitrophyre facies of the ignimbritic deposits and 13 samples of glassy facies of porphyritic rhyolitic lava flows having the same chemical affinity.
Most particularly, the vitrophyre samples from Mesa Cajon de Acuna in Rayon (Sonora) fall in the same group (with higher Sr content) as the Catavina samples (Olguin-Villa, 2010; Olguin-Villa et al., 2010, Gomez-Valencia and Vidal-Solano, 2010; Olguin-Villa et al., 2013).
In that location the ignimbrite does not have a defined base, with a vitrophyre, but rather appears to continue downward into fluidal rhyolites, suggesting that the ignimbrite corresponds to an intracaldera facies rather than an outflow sheet.
The LFU ([less than or equal to]190 to [less than or equal to]40 m) is a medium- to coarse-grained, massive, columnar jointed basalt of dominantly holocrystalline texture with minor vitrophyre. The top few metres are often amygdaloidal and mafic pegmatites locally occur with felsic layers ([less than or equal to]2-3 cm).
It is a massive, columnar jointed basalt with a medium- to coarse-grained texture and contains abundant vitrophyre ([less than or equal to]30%).