New to rock hounding with a couple what is questions

[Southwind]

I know I live in perhaps the worst location for finding even simi-precious stones, but hey, I've never let that stop me before. I went on my first rock hunt today and found a few I have questions about.

On the flat piece of stone with the round hole in it I have two pieces. The first looks to be very clear perhaps my first Kansas diamond?. In with it is a stone that seems to have a diamond shaped formation with some shiny piece impeded in it. Like some kind of mica. Any ideas?
Thanks

 

[Dave J.]

The larger one is agate (a variety of cryptocrystalline quartz) with a couple patches of hematite staining. The shiny spot looks like a crystalline inclusion or the flat spot remaining after a crystalline inclusion broke out, can't tell from the photo. It's not unusual for cryptocrystalline quartz to have a greasy surface appearance. (Diamond virtually always does, but doesn't look like agate).

The smaller one is very probably quartz, and probably crystalline rather than cryptocrystalline. Not really diamond of course, clear crystalline quartz is called "diamond" in some localities which produce distinctive clear quartz specimens.

What was the geological setting in which these were found?

 

[Southwind]

Found in southwest Kansas on the Arkansas river.

Thanks

 

[Dave J.]

So probably river gravel washed down from the Rockies?

 

[Southwind]

Yes! I've been told there was gold in this river as well washed from out of the Rockies. There were prospectors in the past but the content was too low to be worth working.