Please help identify my rock

[brandoniparsconi]

Found this along the Icicle River near Leavenworth, Washington

 

[vpnavy]

I noticed this was your very first post - so, Welcome Aboard brandoniparsconi!

 

[Eu_citzen]

Will a knife scratch it? Looks like a rock rather then mineral; my mind wanders towards greenstone.

 

[brandoniparsconi]

It’s definitely a rock, and by definition it’s a rhythmite since it’s layers are only two kinds of material. At least, that is my understanding. It think it came out of a rhythmite embankment and fell into the river and took on this shape. I just don’t know why the river didn’t wear smoothie the rough layers.