South Yuma Mine: Willemite Rockhounding in Pima County, Arizona

Quick details

Access

Permission required

County

Pima County

State

Arizona

Nearest road

Coyote Pass Trail

Postcode

85743

Coordinates

32.31475, -111.12211

Geology at South Yuma Mine

This spot sits on volcanic rocks, mapped as rhyolite, dacite, and andesite that formed roughly 84 to 48 million years ago. Volcanic ground like this weathers into rocky slopes and float, and fresh exposures in cuts and drainages are usually the most productive places to look.

Mapped unit

volcanic rocks

Age

84–48 Ma (Late Cretaceous to Early Eocene)

Rock types

rhyolite, dacite, and andesite

Elevation

2,560 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.

Land & collecting status

Permission required before collecting

Requires landowner or agency permission before any collecting. Do not enter without explicit authorization.

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.

State guidance last verified: April 1, 2026

• BLM Arizona, Recreational Mineral Collecting
• Arizona Geological Survey
• Arizona State Land Department recreation permits
• Community submissions reviewed against published agency rules

Found at South Yuma Mine

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

• Willemite