How do the stripes happen?

[Wonderist]

These are from Flathead lake, in Montana.
I’m curious about how the rock is formed with the stripes- how do the materials interact to create that result?
Is the white stripe always the same material?
Also, what material is the green rock?

Thanks!

[Hal Gorges]

Welcome from Florida, Some of the rock solid folks will know, how to explain it..I’m told we don’t have rocks in Florida...P.S. don’t take most of what I say seriously, and have some fun..

[CMD]

Roger(painshill) can give you a good explanation, and hopefully he will see your thread. But, you need to understand none of those pebbles formed the way you see them. They all would have originally been part of thick formations, perhaps thousands of feet thick. The quartz veins would have reflected events in which molten material would have flowed and later cooled. Here are some pages that may help get the idea across. But start with the fact that these pebbles are the end product of eons of weathering. Originally, they would have been part of formations, be those formations sedimentary deposits, or metamorphic, or igneous. They did not start their life as the pebbles they are now.....

https://en.wikipedia.org/wiki/Vein_(geology)

Note: I have no idea why the above link gives that result. I copied the correct page. At any rate, click on “did you mean vein geology?” and you will go to the page I copied in the first place.....

http://earthsci.org/mineral/mindep/vein/vein.html

[Hoss]

https://en.wikipedia.org/wiki/Vein_(geology)

[Hoss]

No idea why Charl it is doing it to my link too.

[CMD]

Another useful page....

http://www.quartzpage.de/gen_occ.html

[antmike915]

Very cool, looks like the love child of quartz and some brown stone.