Isosceles Triangle 11lb stone

[Stevie G]

Found this while kayaking an desolate shoreline in Georgian Bay. 19inches on both lengths. Extremely dense, not shale. Maybe some markings but not too sure. I am waiting for it to magically glow (kidding). Not sure if nature can create a close to perfect isosceles triangle.
Any thoughts out there?

 

[E-Trac-Ohio]

Very interesting !

 

[Stevie G]

Very interesting !

Do you think I should continue to wet sand it?

 

[Gare]

What is it made of ?

 

[Stevie G]

What is it made of ?

I am not sure. Very heavy and dense like marble. Not typical of the area.

 

[ToddsPoint]

It looks like limestone. Sedimentary so that will give you the consistent thickness. Relatively soft so can be shaped by water easily. Limestone is not durable so it wasn’t used very often by natives to make tools or much else. Natural in my humble opinion.