Pa-231/U-235 and Th-230/U-234 ages were determined for 17 carnotites f
rom two areas in Israel. For this purpose, a simplified one-step metho
d was used to purify the protactinium, the extraction into TTA (thenoy
l-trifluoro-acetone) at high acidity. Using the test of concordance be
tween the two dating methods, 12 of the 17 carnotites were found to ha
ve acted as closed chemical systems whereas 4 seem to have gained uran
ium. The details of the relationships between the (231)pa/U-235 and th
e Th-230/U-234 ages suggest that the uranium gain which took place in
the latter 4 cases, occurred in a manner which was approximately conti
nuous and linear.