Blacks Fork

Blacks Fork is a river system draining the Uinta Mountains into the Green River drainage across southwestern Wyoming's Uinta County. The northeast portion of the Blacks Fork area is a known rockhounding spot for what's commonly (if inaccurately) called "turritella agate" — actually silicified Goniobasis freshwater snail fossils from the Eocene-age Laney Member of the Green River Formation, roughly 42-53 million years old — along with chalcedony, jasper, and quartz crystals. This is open, high-desert public-land terrain typical of southwest Wyoming, though land ownership in this part of the state often follows a checkerboard pattern of alternating public (BLM) and private/state sections tied to old railroad land grants — confirm you're on public ground before collecting.

The Blacks Fork area lies in Uinta County, southwestern Wyoming, in the Green River drainage south of the Wyoming Range. Specific road access was not verified in this research — general position is the northeast portion of the Blacks Fork drainage.

Surface collecting — walk exposed ground and washes looking for the silicified snail-fossil "agate," chalcedony, and jasper. No digging required for most float material; a rock hammer helps for breaking larger pieces.

Southwest Wyoming's land pattern here is a checkerboard of BLM and private/state sections. Confirm you're on public land before collecting — check BLM public land survey maps or a land-ownership app before heading out. See BLM Wyoming's general rockhounding guidance for background.