The volatile parts of a planet's atmosphere or crust(noun)
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Use "volatiles" in a sentence
"Once the curry bubbles, add the pineapple pieces and cover and simmer for just 2 mins more and cover to let the volatiles from the spices flavor the gravy."
"However, it appears that the moons of Mars may be captured asteroids and could be abundant in volatiles."
"Pumice is a type of extrusive volcanic rock, produced when lava with a very high content of water and gases (together these are called volatiles) is extruded (or thrown out of) a volcano."