Wow, you are a biochemist. So sorry!
Excellent answer, but as I feared, my question was poorly framed.
I imagine high-temperature superconductors and clays have a lot in common with their layered structure, albeit at different scales. My imagination may have overrun my common sense, again.
In acidified zeolites, for instance, an atom may be replaced by another species that provides a location for the extra proton within the pores of the catalyst. The pH is only 'felt' if the reactant is small enough to enter the pore. How the heck do you make an alkaline clay that has the right 'surface'?
Man, I re-read your original answer in trying to reframe my question, and I'm addled. It isn't 'why does this work?', but more of a 'How'.
Sit by my fire, talk medicine with me.
Why does this work as opposed to how does this work.
Why and how are usually related to each other.
I gathered from the literature that 'how' isn't answered yet, they're still in the process of working that particular little detail out.
There are a couple of clues in the abstracts linked to at the end of the article that you linked to.
The first one being that the activity of the clays is pH dependent, and the second one being that the activity is carried in the leachate.
QUOTE
Cation exchange procedures remove the antibacterial component of the clay, and leachates are shown to effectively kill bacteria.
http://gsa.confex.com/gsa/2007AM/finalprog...ract_127547.htmAFAIK clays usually take the form of sheets of aluminosilicates. It sounds (to me at least) like the active part of the clay takes the form of something that is normally bound between the sheets of aluminosilicates.
Allow me a moment of speculation here.
They designate it as CsAg02. We also know that it contains Iron (I think Iron II given the green colour).
My speculation is this - that in the space between the phyllosilicate sheets, there is a water soluble complex, probably polycationic, and probably a complex containing a Silver center (i'll explain this momentarily).
I suggest a silver center because of the designation CsAg02 could represent a partial replacement of Fe(II) ions withe Caesium and Silver, and Silver does have known bactericidal properties, so that wcould explain something, and it seems within the realms of possibility at least anyway.
It also seems (to me at least) consistent with he designation CsAr02 - sometimes things can be shorthanded to what's different, for example short handing the electron configuration of Argon as [Ne] 3s2 3p6. Aside from that, although Argon is a noble gas, at the same time it does form clatharates and excited state complexes, and given that it is as soluble in water as oxygen, and the most common noble gas, it seems reasonable to expect that it could become bound within clays.
So at this point my best guess on how is that it's a heteropolycationic complex - and silicates/alumino silicates can make some large molecules, possibly with a silver center (I say that because I know nothing about the bioactivity of Caesium - asid from it occasionally replaces potassium, and less about it bacterial toxicity) that maybe acts in an analagous way to penicillin - interfering with DD-transpetidase.
The pH can be important in that it, for example, can control the ionization of functional groups. I don't recall which of the enzymes it is, but there's one in the human stomach that has two organic acid groups in it's active site. If memory serves, there's a narrow range of pH's, I think it's between 1 and 3, where it's activated. This is because in order to work correctly it requires one of the acid groups to be bound to a proton and not the other, go too far in one direction, both groups have protons, too far in the other direction and neither have protons, in both cases, the enzyme is no longer active.
So that fact that it's activity is pH dependent suggests that there's a crucial OH group that's removable. Why this should be the case is unclear (at this point) but I do know that the function of Haemoglobin in the body is crucially dependent on the placement of 4 hydrogen atoms above the active metal site, I don't remember the details, but I think the hydrogen atoms affect the Oxygens antibonding HOMO, which in turn makes it easier (and more efficient) for the oxygen to leave the Haemoglobin.
It could also just be that the OH group is neccessary because whatever this complex is acts to hydrolyze some crucial bond, whether it be in the DD-transpeptidase, or in the peptidoglycan layer itself - this could explain why it's harmless to humas as well, because if it's acting specifically and directly on the peptidoglycan layer, breaking it down by hydrolyzing it, then it would be lethal to bacteria, but harmless to us, because animal cells have no cell wall.
So, to recap:
My best guess as to how it works, based on the information available is that it's some kind of heteropolycationic complex with a silver center, that possibly relies on the hydrolysis of DD-transpeptidase, or directly attacking the petidoglycan layer of the cell wall, which is present in Bacterial cells, but not animal cells, and this complex is normally weakly bound in the space between the phyllosilicate sheets.
The evidence which leads me to believe this are: The knowledge of the bactericidal properties of silver (no, I haven't looked into the mechanism of that), the fact that the leachates are active in the same way as the clay itself, and the fact that the activity of the clay is pH dependent (also, if the heating is dehydrating rather then oxidizing the complex, that could provide some insight as well).
I'll gladly sit by your fire and chat about what I can.
) 
