Siliceous sedimentary stone?

[Durandus]

Hi all!

I've been coming across a few of these kinds of stones while rummaging about in rockpiles in Central Mn. and have not, as yet, quite figured out what they are. They have a glassy appearance, so I'm supposing they have arrived by glacier forces. In magnification they are composed of fine grains of red, yellow, grey, green and brown (quite heavy for their size, being about that of a softball), some combination of chert as I imagine. What are your observations/insights? Perhaps the last, yellowish stone is a kind of agate?

 

[curbdiggercarl57]

You might want to smash one, if the fractured pieces appear to be almost glass-like, then it may be chert.
To me, it appears to be water worn chert, but I've been known to smell colors.
Carl

 

[DrJoePrime]

I'd like to see some natural light photos..both in sun and shade. The flash gives a false shiny appearance.