The phrase "rock fragments" refers to pieces or broken parts of rocks.
Sentences with «rock fragments»
At least one team has discovered water - rich rock fragments in volcanic debris originating from the mantle. (newscientist.com)
When rock fragments fall into the magma chamber, all fluids inside boil instantly. (sciencedaily.com)
When rock fragments fall into the magma chamber, they are rapidly heated by several hundred degrees, and all fluids inside boil instantly. (sciencedaily.com)