The "Gertrude Weise" material is non-crystalline silica, which rules out it being a sedimentary deposit from the erosion of crystalline rocks. Rhyolite often contains large amounts of opaline silica, but I've seen no evidence that any of the volcanic rocks in the area are rhyolite. Diatomite or diatomaceous earth are composed of non-crystalline silica.

The "Gertrude Weise" material is fine grained and white to cream in color. Diatomaceous earth is very fine grained and white to cream in color.

NASA suggested the possible origin as the " interception of soil with acid vapors." I do not understand the mechanism where the passing of acid vapors through a soil could produce granular "high grade" silica soil. they also suggested that it could be produced in a hot spring enviornment. Hot spring deposits are generally travertine, a calcium carbonate rock.

There is the possibility that diatoms are ubiquitous throughout our solar system.