First observations of sporadic iron layers (FeS) at low and middle southern latitudes are reported. These and new measurements from northern polar latitudes are combined to study the latitudinal dependence of FeS layer properties and their correlation with simultaneously observed sporadic E layers (ES). We also compare the individual properties of FeS and sporadic sodium layers (NaS): (1) The overall appearance rate for FeS is much higher than for NaS. (2) FeS layers do not show the marked minimum in appearance. (3) Both the normal and the sporadic Fe layers are considerably more dynamic than in the case of Na layers. (4) Concerning the shape, FeS layers are typically broader, slower in growing and longer lasting than NaS layers. (5) The dependence of appearance rate of sporadic metal layers versus local time and latitude shows a complex pattern. (6) The correlation with ES appears to be weaker for FeS than for NaS.