Eldorado Rhyolite Alterations (quartz, epidote, aldularia)

Rhyolite Lava and Ash of the middle Patsy Mine Formation volcanics. Tpm - Middle part, undivided—Rhyolite lavas and interbedded tuffaceous sedimentary (ash fall) rocks. Patsy Mine Volcanics are divided into upper, middle, and lower informal parts. Upper and lower parts are predominantly andesite and middle part is mostly rhyolite. Patsy Mine Volcanics are bracketed by Peach Springs Tuff with an age of about 18.5 Ma and Tuff of Bridge Spring (Tb) with an age of about 15.2 Ma.

Colorado extensional corridor of 100% east-west extension would have our block 3 million years of lava layers tilting 30 degrees down into the graben with all tilted rock ages then exposed by erosion. The oldest lavas of the west are topographically higher than the younger eastern layers. Normal faults between the books on the bookshelf create each books surface hogback... maybe.

The gas bubbles for the geodes probably on rising to the surface of the viscous lava without bursting while the lowering pressure converted the hot gas (chalcedony banding) to liquid for macro quartz crystal growth... maybe.

Know your lavas:
https://www2.tulane.edu/~sanelson/Natural_Disasters/volcan&magma.htm

Know your quartzes:
https://www.youtube.com/watch?v=J1KmmzVxwlk

Free Geologic Map. (at the very south map edge and west of Hiway 60):
https://pubs.usgs.gov/of/2013/1267/a/

Eruption Van Halen cover on Youtube:
https://www.youtube.com/watch?v=GTvcyYUWV2M