Two strange metal detecting finds

[timekiller]

I found a black chunk of material that sets the metal detector off and is extremely light weight. Muritic acid doesn't affect it at all. It is pitted. I have no idea what this could be. Also, I found a grayish color metal that has a very heavy weight property and is harder than lead. Muritic acid doesn't affect this metal either. Any ideas or suggestions.

 

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[detector de metales]

Nice what's it..
I agree with the top one coal or coal byproduct. I once was at an old railroad yard with a buddy and we got so frustrated @ the coal chunks coming up that we left for happier places..
The bottom one needs more information, you say muriatic acid doesn't react with it? To tell you the truth it looks like lead from the pictures, there seems to be a melted spot on the top of the first picture and pitted in the second. If you take a plumbers torch to it does it melt?

J2

 

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[SWEATYSOCK]

top pic is probably a bit of lung, coughed up by the marlboro smoker

 

[taz42o]

I did a demolition job in PA along Ohio river large tar or asphalt tanks 70' tall they were heated inside with gas burners the outside of tanks were covered in blocks of insulation material that looked just like the black piece you have. I thought it was carbon but dont know for sure.