natural glass
- noun
- /ˈnæʧərəl ɡlæs/
- Specialized
- Fossil evidence shows that Stone Age humans used this natural glass to make tools, such as spearheads and cutting instruments, as far back as 9,000 years ago.
Examples
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This stunning piece of natural glass showcases the unique textures created by the rapid cooling of molten rock.
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Obsidian is a dark, natural glass formed when lava cools without crystallizing.
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The background was made by an image of a piece of natural glass and another of leaves covered in frost, combined by applying the Color Mode.
Academic text (1999) -
Fossil evidence shows that Stone Age humans used this natural glass to make tools, such as spearheads and cutting instruments, as far back as 9,000 years ago.
Blog text (4)
Synonyms
A hard clear material made from sand used for windows and bottles
A hard shiny rock made when hot lava cools and hardens very fast
Surface Forms
Morphology
The phrase simply combines 'natural' (occurring in nature) with 'glass' (the material), so a B1 learner who knows both words will understand it as glass that occurs or is produced by natural processes. The detailed geological formation (rapid cooling of magma) is additional factual information but not required to grasp the core meaning, and the compositional pattern is cross-linguistically common.
Etymology
Natural glass is rock that forms when very hot lava cools so fast that it becomes shiny and smooth like 'glass'. So, because it looks and breaks like 'glass' made by people, for example obsidian, we call it natural glass today.