For God's sake barry, don't ever cut and paste in that form again. Edit out the spaces for everyone's sake!

(I always reckon it's wrong to be "too busy" to fix up punctuation and spelling, since everyone else has to waste time trying to read it, especially when it's as bad as this!

MN CARBONATES IN THE MARTIAN METEORITE NAKHLA: POSSIBLE EVIDENCE OF BRINE EVAPORATION

Mn Carbonates as Indicators of Microbial Activity: The possibilities for either biogenic or abiotic origins , or perhaps a combination of the two, need further investigation. On Earth, low-temperature Mn carbonate precipitation is often microbially mediated. Significant amounts of biotic manganous carbonate have been discovered in the Baltic S ea [14]. Additionally, bacterially precipitated rhodochrosite has been produced under laboratory conditions by Geobacter metallireducens [15]. Future studies using ion microprobe analysis of 13C / 12C and 34S / 32S may be able to differentiate between these two possibilities . Stable isotope fractionation on Earth can be used as an indicator of microbial activity because metabolic processes can lead to enrichment in the lighter isotopes of carbon and sulfur. The microscopic textures of the carbonates in this study also exhibit a complex morphology. The possibility that this texture could have been produced by either abiotic processes or through biological activity underscores the need to develop good criteria for identification of microbial precipitates .

Not the world's strongest abstract - lot's of "possible", "may be", "could have been", and the first sentance is a cop-out "either biogenic OR abiotic origins" but then - "or perhaps a combination of the two" In the context of Mars meteorites, the vital question is:

Is there ANY biogenic component, or not?

The fact remains that at the 6th Mars conference McKay was a much quieter and chastened person, trying to return to non-contentious research, IMHO.