  Clusters of galaxies are massive enough to be considered representative
samples of the Universe, and to retain all of the heavy elements synthesized in
their constituent stars. Since most of these metals reside in hot plasma, X-ray
spectroscopy of clusters provides a unique and fundamental tool for studying
chemical evolution. I review the current observational status of X-ray
measurements of the chemical composition of the intracluster medium, and its
interpretation in the context of the nature and history of star and galaxy
formation processes in the Universe. I provide brief historical and
cosmological contexts, an overview of results from the mature ASCA observatory
database, and new results from the Chandra and XMM-Newton X-ray observatories.
I conclude with a summary of important points and promising future directions
in this rapidly growing field.
