What is it?

[Reign9005]

I found this in kansas, it measures 12" long × 6" wide × 3 1/2" thick. It's heavier than it looks.

 

[Icewing]

You need to find some local rockhounds

 

[A2coins]

Looks like granite mixed with quarts just an uneducated guess

 

[Back-of-the-boat]

It looks like a quartz vein running through green schist.IMO

 

[Charlie P. (NY)]

I don't know. It looks pretty heavy.

Rock that cracked and the cracks filled with silicate/quartz.

 

[wallrat_1975]

The third pic looks like a fossilized Big Foot track