We characterize a ‘‘ring-cluster’’ (RC) structure produced by high temperature annealing of transition metals on Si(111), studied by scanning tunneling microscope and low-energy electron microscopy. This structure consists of a single metal atom on a substitutional site in the top layer of Si(111) plus an overlying ring of six Si adatoms with an unusual bridge bonded topology. We find that the same structure occurs for all near noble metals specifically Fe, Co, Ni, Pd, Pt and Ir. It does not occur for refractory metals (Ti, W) or for noble metals (Cu, Ag). Clear phase separation of clean Si(111)-7×7 and large triangular domains containing a lattice gas of RCs occurs only for quenching from above the 7×7 to 1×1 phase transition at T=840 °C. The density of RCs within a domain increases with average metal coverage. The domain orientation is defined by its boundary with the faulted half of 7×7 unit cells. The large scale morphology for RC induced structures and its dependence on quench rate suggests a precipitation reaction. Dissolution rate of nickel RCs into bulk Si was found to be t=20 s at 800 °C assuming exponential decay.