Rock ID Help Please

[Kaolin washer]

my best guess is diabase basalt fine grainedis it magnetic
?

[Node]

Not Magnetic

[Node]

Correction.  This rock is not magnetic in that it attracts ferris metals, but it is magnetic in the sense it attracts a magnet.  

[Node]

On 7/16/2020 at 12:55 PM, Snoball Solar System said:

That's a greywacke river cobble, but the interesting thing is the nodular brown rock scale, on 'one side only'.

I suggest that the nodular brown rock scale is comet spatter delivered to southern WI by way of an eject curtain composed of ice sheet fragments, from a primary (Clovis comet) impact on the Laurentide ice sheet, 12,800 years ago.  The rock scale is on the side of the river rock exposed to the secondary impact, which is why the scale is on one side only.

These same massive ice sheet fragments are suggested by others to be responsible for creating the Carolina bays along the Atlantic and Gulf coasts.

I like the theory on this but the rock has the black crust on all sides.  It's just more prominent on two of the sides. the sides with less black crust seems to be more weathered as well.