Help with id please

[PennyG]

Rocks were found in Illinois on the beach of Lake Michigan .
Picture number one , the two appear to be reflective. Not sure proper terminology

Picture number two. The purplish rock with white. Once wet looks completely dark purple.

Picture number three. Rocks have pinkish to orange spots, wondered if they are agates.

 

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[stdenis_jd]

Looks like quartzite for the purple one, top pic also appears to be a different variety of quartzite, pic 3 looks like gowganda tillite

 

[EricTheCat]

I wonder if pic 3 could be agate in matrix. I cannot tell from the pic but I have found very similar looking rock and on mine there is banding evident on the lighter pockets and shows that it formed in pockets of the host rock (matrix). From the pic (and a quick search) it does also resemble gowganda tillite as stdenis_jd mentioned. You might be able to tell with the rock in hand which is more likely.

 

[stdenis_jd]

If it's tillite, the pinkish spots will look like feldspar/granite (really granular looking) if it's banded like rings and or clear/translucent material then you've got like Eric said some kind of agate in matrix like basalt or something

 

[PennyG]

Thanks guys. Here a few closer shots

 

[PennyG]

The large one weighs a pound. Nice size.

 

[stdenis_jd]

O yeah, there's clearly banding in pic#1 of those last pics. Agate of some kind mixed in there. I don't have extensive enough knowledge to know much more about it though but I would guess it's still a tillite (imagine agates lying in mud then getting a couple miles of glacier sitting on top of them)

 

[PennyG]

I have a tile saw. However , I'm a little scared to use it to cut rocks that large. I've read a lot of scary reviews. Any recommendations ?

 

[EricTheCat]

That banding that can be seen in the 2nd set of pics really makes me think agate in matrix. Agates form in gas pockets in a host rock (basalt typically around here at least). We find agates separate after glaciers and things have broken the agates free from the host rock. Sometimes you can find pieces of the host rock that still have agate pockets in them. That's just my 2 cents as I am no expert and certainly cannot prove stdenis_jd's interesting idea wrong.

Here are some pics of what I believe is 2 agate in matrix from the North shore of lake Superior. Whatever they are they sure look similar to yours.

 

[PennyG]

Y'all are all so awesome. Thank you again for the informative answers. I took a dremel to the larger rock last night. Kept getting red mineral off the top layer. I barely removed any but I can see a tad bit more banding. [emoji4]