[TheForge] OK, now I'm mildly perplexed...

[Andy Vida]

Well, I just finished etching a link of that wrought iron roller chain
I dug out of the river two days ago.

The grain is fine, which I expected, but what I didn't expect was the
seemingly high silica content.  I've etched quite a lot of wrought iron
and the quality has ranged from basically muck bar to highly refined.
In no case did I ever get such a glassy sheen.  I'm assuming this 
indicates a higher proportion of iron silicate (where's Hochella when
you need him?).  Is this in fact the case, or is this odd visual
the result of something else?  I etched in HCL to exhaustion.  Could
the ferric chloride have caused this?

Odder still:  the PINS are also wrought iron.  I have yet to etch a
roller, but I cannot imagine they'd also be wrought.