Thank you for this: "BTW, silicon does burn -- just like charcoal -- once you get it hot enough. Instead of carbon dioxide -- you get white sand. (Silicon dioxide)
The reaction throws off plenty of heat, too. At least it's not a stinky reaction -- but the rest of the stuff is."
I hope to have time to stop at the site tommorrow and check the removal progress. Also to find out if any definitive cause, or location of point of origin has been determined.