The potential of the 26 Al isotope for exposure and burial dating applications has not been fully realized to date due to the low efficiency for producing the Al − ion in negative ion sources. Here, we show that it is possible to use the AlO − ion instead, which is produced an order of magnitude more efficiently, provided that a gas-filled magnet is employed to reduce the intense flux of 26 Mg ions at the detector. It is then possible to achieve comparable counting statistics for 26 Al as for the much more widely used 10 Be.