Rosston: Aragonite Rockhounding in Harper County, Oklahoma

Quick details

Access

Check locally

County

Harper County

State

Oklahoma

Coordinates

36.91541, -99.87347

Geology at Rosston

This spot sits on Marlow Formation, mapped as sandstone and siltstone that formed roughly 300 to 250 million years ago. Sedimentary rock like this erodes unevenly, so the most productive collecting is typically along fresh cuts, badland slopes, and active drainages.

Mapped unit

Marlow Formation

Age

300–250 Ma (Permian)

Rock types

sandstone and siltstone

Elevation

2,070 ft

Geologic mapping via Macrostrat and the underlying state geological survey maps (CC BY 4.0). Bedrock at the surface can vary within a mapped unit.

Best time to visit Rosston

Best months: September to June. Typical highs run 94°F in midsummer and 48°F in midwinter, with winter lows near 22°F.

Climate normals: NOAA 1991-2020 monthlies, GATE station (11 mi away), adjusted for elevation.

Land & collecting status

Confirm rules before collecting

Land status here is not confirmed. Verify with the managing agency before collecting — federal, state, and tribal rules differ.

Public-land rules vary by agency, season, and field office. The RockHoundR app pulls live BLM, USFS, NPS, and tribal overlays so you can see exactly which agency manages the ground at this spot.

Sources & verification

Spot details combine the public RockHoundR location dataset, normalized mineral labels, agency land-status checks in the app, and community submissions. Coordinates are approximate until verified in the field.

Sources: RockHoundR public spot dataset, app land overlays, and local agency review before each trip.

Found at Rosston

Each chip opens all spots that produce that material; the encyclopedia link opens the full ID and field guide.

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