The IsoTrace heavy element AMS system has been successfully used to de
tect the naturally occurring U-236 (U-236/U-238 (5.6 +/- 1.5) x 10(-10
), based on a single measurement with a 1sigma confidence level) in sa
mples of the uranium ore from Cigar Lake, Saskatchewan, Canada. This l
evel of U-236 agrees with that previously claimed for samples of a pro
cressed uranium ore [1], and is consitent with the amount of Pu-239 fo
und in pitchblende [2].