  High resolution spectroscopy is used to determine the detailed chemical
abundances of a group of eight F- and G-type stars in the young open cluster
Blanco 1. An average [Fe/H] of +0.04 +/- 0.02 (internal error) +/- 0.04
(external error) is found, considerably lower than a previous spectroscopic
estimate for this cluster. The difference is due mainly to our adoption of
significantly cooler temperatures which are consistent with both photometric
and spectroscopic constraints. Blanco~1 exhibits sub-solar [Ni/Fe] (-0.18 +/-
0.01 +/- 0.01), [Si/Fe] (-0.09$ +/- 0.02 +/- 0.03), [Mg/Fe] (-0.14 +/- 0.02 +/-
0.03) and [Ca/Fe] (-0.09 +/- 0.03 +/- 0.03); ratios which are not observed
among nearby field stars. The material from which Blanco 1 formed may not have
been well mixed with interstellar matter in the galactic disc, which tallies
with its current location about 240pc below the galactic plane. A simultaneous
deficit of Ni and alpha elements with respect to Fe is hard to reconcile with
most published models of yields from supernovae of types Ia and II. The revised
abundances for Blanco 1 indicate that overall radiative opacities in its stars,
and hence convective zone properties at a given mass, are similar to those in
the Pleiades at approximately the same age. This can explain a previous
observation that the Li depletion patterns of G- and K-type stars in the two
clusters are indistinguishable. The lower overall metallicity of Blanco 1 now
make it less attractive as a target for discovering transiting, short period
exoplanets.
