# abyssolith

CEFR C2 · Noun

Source: https://englishreference.com/word/abyssolith
Updated: 2026-05-18

## Definition

a type of rock that forms when magma cools very slowly deep inside the Earth. It is usually dark and has a smooth, glassy surface.

For teachers: a rock formed by the slow cooling of magma at great depths within the Earth's crust. Characterised by a fine-grained or glassy texture and typically dark in colour.

## Examples

- The geologist identified the sample as an abyssolith.
- The deep-sea volcanic vents produced an abyssolith that remained hidden from the surface for millions of years.
- Unlike extrusive igneous rocks that cool rapidly on the surface, abyssoliths exhibit a homogeneous structure due to the immense pressure and slow crystallisation process occurring kilometers below the Earth's crust.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.