A search for cosmic-ray produced Al 26 has been undertaken in meteorites and tektites, using γ—γ coincidence spectrometry. The sensitivity and specificity of this method were sufficient to permit non-destructive measurement of Al 26 in a 70 g specimen of the Plainview chondrite; the specific activity found, 0·058 ± 0·005 positrons min -1 g -1, agrees well with the value of EHMANN and KOHMAN. In the case of tektites, chemical separation of the aluminium fraction was required because of interference by the U and Th series. Although a very small amount of activity was found in the aluminium fraction from an australite, corresponding to an apparent Al 26 content of 0·005 ± 0·009 positrons min -1 g -1, and a "flight time" of 1·1 ± 2·0 × 10 5 years, it is shown that even this low counting rate was due to some contaminant, rather than Al 26. Corrected for this contaminant, the counting rate becomes 0·000 ± 0·009 positrons min -1 g -1, and the upper limit for the Al 26 content of australites, ⩽ 0·022 disintegrations min -1 g -1 in contrast to the Ehmann and Kohman value of 0·040 ± 0·011. This limit corresponds to a "flight time" of ⩽ 5 × 10 5 years. In view of this result, a terrestrial origin of tektites has once more become a possibility.