volcanic glass
C1Academic, Scientific, Technical
Definition
Meaning
A natural glass formed by the rapid cooling of lava, lacking a crystalline structure.
Any amorphous, non-crystalline solid produced by volcanic activity, most commonly obsidian, but also including pumice and other forms.
Linguistics
Semantic Notes
The term is a hyponym; 'obsidian' is the most common specific type of volcanic glass. It implies a specific geological origin and physical property (amorphous solid).
Dialectal Variation
British vs American Usage
Differences
No significant difference in meaning or usage. The term is technical and used identically.
Connotations
Neutral, scientific descriptor.
Frequency
Equally low-frequency in both dialects, confined to geological contexts.
Vocabulary
Collocations
Grammar
Valency Patterns
[Noun] made of volcanic glass[Noun] composed of volcanic glassvolcanic glass from [Location]Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “None”
Usage
Context Usage
Business
Virtually never used.
Academic
Used in geology, archaeology, and earth sciences to describe material properties and origins.
Everyday
Rare, except in contexts like museum visits, documentaries, or specific hobbies.
Technical
Precise term for amorphous volcanic products in geological reports and papers.
Examples
By Part of Speech
noun
British English
- The archaeologist found tools crafted from volcanic glass.
- The cliffs revealed a stratum rich in volcanic glass.
American English
- The arrowheads were made of volcanic glass sourced from the local mountains.
- This volcanic glass, known as obsidian, fractures with very sharp edges.
Examples
By CEFR Level
- This black rock is volcanic glass.
- Ancient people used volcanic glass to make sharp tools and weapons.
- The rapid cooling of the lava prevented crystal growth, resulting in volcanic glass.
- Geochemical analysis of the volcanic glass fragments helped correlate the ash layers across the region.
Learning
Memory Aids
Mnemonic
Think: 'Volcano' + 'glass' = glass made by a volcano, not in a factory.
Conceptual Metaphor
SOLIDIFIED LIGHTNING (captures the idea of rapid, energetic formation resulting in a frozen, sharp substance).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid direct calque 'вулканическое стекло' in non-scientific English conversation; 'obsidian' is more common in general contexts.
Common Mistakes
- Using 'volcanic glass' to refer to any shiny volcanic rock (many are crystalline).
- Confusing it with 'pumice', which is a frothy volcanic glass.
Practice
Quiz
What is the primary characteristic of volcanic glass?
FAQ
Frequently Asked Questions
No. Obsidian is the most common and familiar type, typically dark and solid. Pumice and scoria are also forms of volcanic glass but are frothy and full of vesicles (holes).
Yes, historically and in modern times. Its conchoidal fracture allows it to be knapped into extremely sharp tools, blades, and arrowheads. It is also used in surgery as obsidian scalpels and as a gemstone.
It forms when viscous, silica-rich lava cools so rapidly that atoms do not have time to arrange themselves into an ordered, crystalline structure. This results in an amorphous solid, or glass.
Chemically, they can be similar (both are amorphous silicates). The key difference is origin: volcanic glass is a natural product of volcanic activity, while manufactured glass (like window glass) is a human product from melting and cooling silica sand.