Pyroclasts

Part of speech: noun

Definitions

1. Fragments of volcanic rock that are ejected during an explosive eruption
2. Pieces of material that cool and solidify as they are hurled from a volcano
3. Solid debris from a volcanic eruption that can range in size from fine ash to large boulders

Etymology: "Pyroclasts" is the plural of "pyroclast," and the word is built from two Greek-derived pieces. The first, "pyro-," comes from Ancient Greek "pûr," meaning fire, which traces back to an ancient Indo-European root shared by many words for fire and heat. The second, "clast," comes from Greek "klastos," meaning broken, the same root behind words like "iconoclast," the breaker of sacred images. Put together, a pyroclast is literally a "fire-broken" fragment: rock that was shattered and hurled into the air when a volcano erupted. The term belongs to modern geology rather than to ancient usage, since Greek and Roman writers had no need for a word describing volcanic debris in this technical sense. Geologists assembled it from classical roots, which explains why the word looks like a chemistry term while describing something as physical as ash and boulders blasted from a crater.

Synonyms: volcanic debris, ash, tephra