What kind of rock is this?

[Godrocks2]

weight - 17.4 lbs

 

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[1320]

Black granite?

 

[Back-of-the-boat]

you might try posting in the rock and gem forum further down the page you might get more informed answers there.

 

[TheCannonballGuy]

Your rock looks like granite containing a LOT of Biotite (black) Mica, and Olivene (green). But I'm just an old long-ago college Geology student and rock hound, not a Mineralogist. Those folks hang out at TreasureNet's "Rocks/Gems" forum. So take Back-of-the-boat's advice and post your rock photos here:
Rocks/Gems

 

[Godrocks2]

Ok thank you

 

[tamrock]

I believe the Cannon ball guy pretty much nailed it. A lot a biotite....it be metamorphic. Not an expert opinion I have, but I have had a lot of field experience monitoring the effects of various type rock on tungsten carbide. I would guess that rock would have a fairly low compressive strength and not contain much in the way of abrasive elements. So the cost per foot in drilling a hole in that rock would be fairly moderate, but I would throw-in the lack of brittleness could be an issue.