This is an outcrop of weathered slate in Bendigo, Victoria. These rings are caused when fluids move slowly through the rock and there are two chemical species, with different diffusion rates, that are necessary for precipitation of a band. The concentrations of the two fluid components move like out-of-phase waves through the pores in the rock. Where the concentrations of the components are right, you get a band. Where the concentrations are not right, you get a gap between the bands. These phenomena take place in colloidal suspension, in this case, and the band that gets precipitated is an oxy-hydroxide of ferric iron (FeO.OH) – rust, if you like.
This is an outcrop of weathered slate in Bendigo, Victoria. These rings are caused when fluids move slowly through the rock and there are two chemical species, with different diffusion rates, that are necessary for precipitation of a band. The concentrations of the two fluid components move like out-of-phase waves through the pores in the rock. Where the concentrations of the components are right, you get a band. Where the concentrations are not right, you get a gap between the bands. These phenomena take place in colloidal suspension, in this case, and the band that gets precipitated is an oxy-hydroxide of ferric iron (FeO.OH) – rust, if you like.
Nice abstract!!