Meaning & use
combustible rock
Last updated
UK/kəmˈbʌstɪbl ˈrɒk/
US/kəmˈbʌstəbəl ˈrɑːk/
Meaning
nouncountable or uncountabletechnical
A rock that can burn and give off heat, formed from ancient plants or other organic matter; coal is the best-known example.
Grammar: Used as a general term: combustible rock is mined.
Patterns
- mine combustible rock
- a seam of combustible rock
Coal is the most common combustible rock.
Miners dug deep for the combustible rock under the hills.
Oil shale is a combustible rock that can be heated to release oil.
Word forms
| plural | combustible rocks |
|---|
Common combinations
- seam of combustible rock
- A thick seam of combustible rock lay under the valley.
- mine combustible rock
- They mine combustible rock for power.
- combustible rock deposits
- Combustible rock deposits are found worldwide.
- burn combustible rock
- Power plants burn combustible rock to make electricity.
Synonyms and how they differ
- coal
- Coal is the most common example, so it is narrower than combustible rock.
- oil shale
- Oil shale holds oil-like matter and needs heating, which makes it a particular kind of combustible rock.
- lignite
- Lignite is soft brown coal and a lower grade of combustible rock.
Word family
- combust verb
- to burn
- combustion noun
- the process of burning
- combustible adjective
- able to catch fire and burn
- combustibility noun
- how easily something burns
- incombustible adjective
- unable to burn
Commonly confused: combustible rock or flammable?
combustible rock vs flammable
Flammable means easily set on fire, while combustible means able to burn but often more slowly.
Practice
Which of these is a combustible rock?
Choose one answer.
Coal burns and releases heat. Granite, marble and quartz do not.
Make it your own
Write a sentence using “combustible rock”, then check it and compare it with the examples above.
Your sentence stays on this page and is not sent anywhere.