Definition

A large crystal that is found within a type of igneous rock called porphyry.

Example

The geologist pointed out the phenocrysts in the rock sample, noting their size and clarity.

Conversation

Have you ever noticed a phenocryst in a rock before?

Yeah, I saw one during our geology field trip last year.

They look so cool, especially when they're so big and clear.

I know! It's amazing how they form in volcanic rocks.

Synonyms & Antonyms

Root Explanation

Phenocryst → It is formed from "pheno-" (from Greek "phainō", meaning to show or to appear) and "cryst" (from Greek "kristallos", meaning ice or frozen). The word describes a crystal that is visible in a rock, showing its presence distinctly among other minerals.

Memory Tip

Think of 'showing' ('pheno-') a 'crystal' ('cryst') that stands out in a rock — that's what a phenocryst is.

Visually Confused Words