Petrified wood in unknown matrix?

[Digger54]

I found this while walking the shoreline of a Saltwater river in SC a few years ago after some storm related erosion. As SC Lowcountry shoreline is sandy with no surface rock formations seeing a rock catches my eye since native Americans would normally bring rock in from inland areas. Have even found points in the same area. It measures 5"X4"X2.75". Weight is guessed at about 2 pounds by standing on a scale with and without it. You can see areas on both sides where tree knots were. With this slate gray color any ideas what the matrix is? No clue how it found itself to the shoreline.

 

[ConceptualizedNetherlandr]

Metamorphic texture.

 

[ArfieBoy]

Nice find!

 

[russau]

My late Father-in-law gave me a chunck of petrified wood (cross section) and it is about 12" x 12" and I have been wanting to slab off a peice of it and polish it down BUT I've been real hesitant to do this ! I don't want to ruin this memory for my wife !