porphyroid

American  

[pawr-fuh-roid] / ˈpɔr fəˌrɔɪd /

noun

1. a rock resembling porphyry.

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

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porphyroid British  

/ ˈpɔːfɪˌrɔɪd /

adjective

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

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noun

1. a metamorphic rock having this texture

Etymology

Origin of porphyroid

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

Example Sentences

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

From The Andes and the Amazon Across the Continent of South America by Orton, James

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

From The Andes and the Amazon Across the Continent of South America by Orton, James

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

From The Andes and the Amazon Across the Continent of South America by Orton, James

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

From The Andes and the Amazon Across the Continent of South America by Orton, James

Dr. T. Sterry Hunt calls them porphyroid trachytes.

From The Andes and the Amazon Across the Continent of South America by Orton, James