Arnold

Arnold is a city in Jefferson County, Missouri, just southwest of St. Louis near I-55. The bedrock here is Mississippian-age limestone, roughly 325–360 million years old — classic geode-forming ground, where cavities in the carbonate rock line themselves with quartz, calcite, and associated sulfide minerals as groundwater deposits minerals over time. That geological fact is well established; what's not independently confirmed is a specific, named public dig site at Arnold itself. The available online references describing an "Arnold geode" spot reproduce the same specimen list this listing is built from almost verbatim, which reads as circular rather than independent confirmation — so this dossier is built on the solid regional geology, not a verified pin.

Arnold sits in Jefferson County, Missouri, along I-55 southwest of St. Louis. No source in this research names a specific parcel, quarry, or creek access point — this listing appears to describe the town/area generally rather than one mapped location.

General inference only: if geodes occur here as the regional geology suggests, the typical method in this part of Missouri is streambed or road-cut surface collecting, not digging or hard-rock work. No source confirms this specifically for Arnold.

Land status is unverified — confirm ownership and permission before collecting anywhere around Arnold. Jefferson County is a mix of suburban development, private farmland, and scattered quarry land; there's no confirmed public collecting site tied to this listing's coordinates.