Porphyritic Texture

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Porphyritic Texture

 

the texture of a rock in which relatively large phenocrysts with regular crystal faces are set in a generally fine-grained groundmass. Rocks with porphyritic textures may be extrusive or intrusive. An extrusive rock with a porphyritic texture has a groundmass that contains an unequal number of phenocrysts and consists of either microlites or glass. An intrusive rock with a porphyritic texture has a finely crystalline and granitic groundmass; for this reason it is also called a granite porphyry.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The petrographic studies show that the Deosai volcanics have porphyritic texture and mainly comprised of plagioclase and hornblende phenocrysts.
In thin sections, these rocks have porphyritic texture. The phenocrysts of plagioclase, hornblende, alkali feldspar and quartz are set in a felsophyric groundmass in a variable amount.
These rocks have glomeroporphyritic and porphyritic texture. The opaque minerals in these rocks consist of chalcopyrite, bornite, malachite, azurite and Fe-oxide.
In its thin sections, the rock has a hypo-crystalline matrix which is composed of porphyritic texture and is rich in a sprinkled opaque mineral, plagioclase, feldspathoid mineral and obsidian.
They have porphyritic texture with plagioclase phenocrystals (up to 10 %) in a subophitic to intersertal groundmass.
Age concordance, the porphyritic textures of the carbonatites and apatite fission track modeling, all indicate rapid cooling from emplacement temperatures.