[David]

Originally Posted by Pusaka

I am not referring to the colour of the two metals, obviously they will vary due to the ratios of copper to tin/zinc. I was referring to the pitting which is not caused by the casting process (why should it be) but due to the fact that there are impurities in the metal.

Why should pitting be caused by the casting process. Because air bubbles get trapped in the mold and leave pits in the surface of the cast. This is a well know effect of the casting process.

Originally Posted by Pusaka

Meteorites are often dirty things and pitting is often the result. This pitting is often but not always observed in thogchag.

Of course meteorites are "dirty things". That is why you must refine the impurities out of them before you work with them. I have seen images of many blades forges with meteoric ore that have no pitting whatsoever.

Originally Posted by Pusaka

Now you have to ask yourself the question did the person who made that keris not have the skill to remove the impurities from that brass mix or did he add them deliberately, Personally I believe the latter

Adding meteorite to this keris would not be adding "impurities". You would simply be adding another purified metal to the process. I am afraid that your line of reasoning here is making little sense to me and i see little use to all this speculation based merely upon internet photographs in furthering any understanding of the make-up of this keris specifically or keris in general.
I suggest that if you want to continue finding an understanding of the materials used to create your pendok that you try having it tested for various metal contents. Certainly it can be tested for gold or silver content. It seems that it has some metal in it's make-up that resists tarnishing, but what that is exactly will remain a mystery until you take the steps to find out.