Small quantities of radon that have been formed by decay of uranium minerals can be found in rock and soil.
(Small quantities of radon; have been formed; by decay of uranium minerals) (Small quantities of radon that have been formed by decay of uranium minerals; can be found; L:in rock and soil)
Small quantities of radon Small quantities of radon that have been formed by decay of uranium minerals
have been formed can be found
by decay of uranium minerals
L:in rock and soil