porphyroid

American

[pawr-fuh-roid] / ˈpɔr fəˌrɔɪd /

noun

a rock resembling porphyry.
a sedimentary rock that has been metamorphosed so as to leave some original crystals in a fine-textured, layered matrix.

porphyroid British

/ ˈpɔːfɪˌrɔɪd /

adjective

(of metamorphic rocks) having a texture characterized by large crystals set in a finer groundmass

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

a metamorphic rock having this texture

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of porphyroid

First recorded in 1790–1800; porphyr(y) + -oid

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Dr. T. Sterry Hunt calls them porphyroid trachytes.

From Project Gutenberg

The solid products of Pichincha since the Conquest have been chiefly pumice, coarse-grained and granular trachyte, and reddish porphyroid trachyte.

From Project Gutenberg

The representative products of Antisana are a black, cellular, vitreous trachyte, a fine-grained, tough porphyroid trachyte, and a coarse reddish porphyroid trachyte.

From Project Gutenberg

Its lithology is represented in our collection by porous, gray, granular trachyte, fine-grained, compact trachyte, and dark porphyroid trachyte.

From Project Gutenberg

Pumice and trachyte are the most common rocks around this mountain, and these are augitic or porphyroid.

From Project Gutenberg

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023