Hey Dave, I think of fishes and dinosaurs. As I feared and kind of knew, the whole question of drusy quartz requires a bit of study. Yes silica from radiolarians is deposted pure chert in beds known as pelagic chert on the ocean floor at depth, but drusy quartz is silica coming out of solution into limestone beds at a shallower depth and so could not be called pelagic. I shall read on! Thanks!

http://www.cliffshade.com/colorado/rocks.htm#pelagic

— I fight to keep arms at my sides, down
from where they’ve been writing
black letters in orange skies.