I do believe kurt is correct in that it is slag of some sort. If you look at the edges you see very little melting that would have occurred from the high temp.of entry through the atmosphere. Also because of that same high temperature the rock would have reached most all organic materials would have vaporized. Which would be simaliar to this. But because of the high content of " space age" materials and iron a meteor would contain you would not see very much cleaving of the edges on impact. Any stone or rock type visable features may also be there due to a molding upon sitting next to rocks and dirt as it rested against them while it cooled. My main background is in manufacturing so I may have overdune the explaination a little. Sorry.
You are doing a great job on these threads. Beautiful top shelf workmanship! It is easy to spot a person who is in love with his or her craft because of the mirror which shows in their product. That is to say it is easy to see their passion!!
Thom