Marble samples from the cathedral at Como and from surrounding quarries have been analyzed for 22 elements by neutron activation analysis. A stepwise discriminant analysis was used to identify the best between-quarry separating elements and these were then used in a hierarchical cluster analysis. The five of the eight Como cathedral samples appeared to classify with the Musso quarry (ca. 40 kilometers north), and the other three with the same quarry but at a greater distance in the cluster analysis. Weathering radically alters the composition of the marble. -- AATA