  Determinations of the chemical composition of red giants in a large sample of
open clusters show that the abundances of the heavy elements La, Ce, Nd and Sm
but not so obviously Y and Eu vary from one cluster to another across a sample
all having about the solar metallicity. For La, Ce, Nd and Sm the amplitudes of
the variations at solar metallicity scale approximately with the main s-process
contribution to solar system material. Consideration of published abundances of
field stars suggest that such a spread in heavy element abundances is present
for the thin and thick disk stars of different metallicity. This new result
provides an opportunity to chemically tag stars by their heavy elements and to
reconstruct dissolved open clusters from the field star population.
