I'm fairly sure now that this is a meteorite. I cut a portion off [see the 2 new pics] with a carbide blade hacksaw, smoothed it on a diamond board, sanded it to 800 fine, and tried to etch it first with vinegar and then with muriatic acid. I read later I should have mixed hydrogen peroxide with the acid, or used nitric acid. But I think the light etching has brought out, not a classic widmanstatten pattern, but some kamacite bands and in the middle, if you zoom, you can make out 2 parallel lines which I think are so called newman lines. These are all indications of an iron meteorite. Not all iron meteorites exhibit the classic pattern, depending on the nickle content. Other indications are the graphite inclusions [my hands got all black sawing], the numerous stress fractures, the fact that it is very hard [they have micro diamonds and it took me over three hours of constant sawing to cut it]. Just to be sure, I've ordered a lab test. Tell me what you think.
James