Any ideas?

Looks like an interesting rock.

Is the greenish stuff in the cracks any oxydation of some type, or is it just dust/dirt?

What have you tried to scratch it with?

Thanks for the quick reply! It's dirt in the cracks, which are perfect circles, I'm assuming where gas/air escaped? It does have a small amount of oxidation, but is rust colored and not much at all. I used a knife and scissors to try to scratch and went to town on it, didn't phase it one bit. I hope this helps?

I guess I should add that it is extremely shiny. The pictures really don't do it justice, but about the best I could do :-)

Could it be some type of metal "slag" from a manufacturing process or something? Is your back yard located any where near a refinery or something?

It's specific density would be a big clue to it's composition. And if you tried scratching it with something of known hardness (like a carbide drill bit or something) that might also give a clue.

You could try submerging it too measure it's volume and then weighing it to calculate it's density (assuming it's not hollow or "foamy" inside of course).

Farmerman may have some better ideas... I'll copy him on the link...

I agree with the slag or clinker from a furnace. It kind of hard to see it clearly but it also could be a kind of volcanic lava like pahoe hoe or aa.

This is to the OP, if you weigh it and then mesure Volume, youd have a value of Weight per unit volume (we could convert that to M/V) the
water displaced.

Does a magnet stick to it? Does it attract a magnet even in the slightest?.

Is it metallic or glassy looking (Thats the part thats hard to tell from the photosd)

I believe that is an alien coprolite . . . looks Venusian to me.

member that alien coprolites is an anagram for ATROPINE LIES COOL>

Have you checked the mail today? Publishers' Clearing House may be looking for you . . .