Strange Rock Please Help Identify

[Lonney hird]

I am hoping someone could help me identify this. I found it at a spot where the side of a mountain had came down, here in northern Pa. As you can see it's only half, it was about 100yrds away from the base.

The outside was all black, and the inside was covered with dirt. As I was cleaning it some or the black flaked off. It looks like the spot was poured into the center of the outer shell. I hope you can see the facets, and something sparkling in a few places. It's approx. 7"x4" and 2" at thickest part. It weighs about 6 - 7 lbs. Looks like the outside was burned,neither the outside or inside react to vinegar or anything. I have been looking thru out the Internet and have found nothing that even looks close. Hope someone knows Thank you

[jasong]

Almost looks like a septarian nodule, but not quite. Maybe something similar though. 

It looks like calcite and siderite inside. Try scratching some of the whitish crystal to powder with a knife or nail, and put vinegar on the powder and see if it reacts (some crystalline structures can act to resist rapid acid reactions). Might try a stronger acid if you have one too, like hydrochloric, or maybe even CLR (or heat up the vinegar - acid is stronger the hotter it is).

I suspect researching Pennsylvania specific geology would expose some suspects though, or maybe someone more familiar with East Coast geology would know specifics. Anything East of the Rockies is foreign to me.