We have formed Mn clusters on Si(111) and Si(112) surfaces and we have examined their magnetic behavior using circularly polarized optical scattering. We show that Mn clusters of diameter 15-25 nm exhibit a temperature dependent ferromagnet-like behavior for temperatures below 10 K. As we use magnetic fields perpendicular to the plane of the surface, our results indicate that the magnetic moment of some of these clusters is out of the plane. In addition, our experiments verify previous theoretical suggestions that polarized optical scattering can be used to detect magnetism in small clusters. (C) 2003 Elsevier Science B.V. All rights reserved.