Sierrita Mountain Mine Dumps: Melanterite & Copper Rockhounding in Pima County, Arizona

Quick details

Access

Public area

County

Pima County

State

Arizona

Coordinates

31.87772, -111.19498

Geology at Sierrita Mountain Mine Dumps

This spot sits on granitic rocks, mapped as diorite, alkali granite, and granodiorite that formed roughly 185 to 145 million years ago. Plutonic rock like this weathers slowly into grus and boulders, and the most productive collecting is typically in weathered zones and drainages.

Mapped unit

granitic rocks

Age

185–145 Ma (Early Jurassic to Late Jurassic)

Rock types

diorite, alkali granite, and granodiorite

Elevation

5,740 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 Sierrita Mountain Mine Dumps

Conditions here are workable year-round, with typical highs from 57°F in winter to 89°F in summer.

Climate normals: NOAA 1991-2020 monthlies, GREEN VALLEY station (12 mi away), adjusted for elevation.

Land & collecting status

Generally open to casual rockhounding

Most public-tagged spots sit on BLM, U.S. Forest Service, or other federal land where reasonable hand collecting of common rocks and minerals is allowed. Confirm posted rules and active mining claims before you dig.

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 Sierrita Mountain Mine Dumps

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

• Melanterite
• CopperEncyclopedia →
• PyriteEncyclopedia →