Derry: Chert Rockhounding in Sierra County, New Mexico

Updated June 2026

Derry is a mapped rockhounding spot in Sierra County, New Mexico. Reported finds include chert. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Sierra County
State: New Mexico
Nearest road: Lost Hill
Coordinates: 32.78832, -107.25309

Geology at Derry

This spot sits on Upper Santa Fe Group, mapped as conglomerate sandstone, coarse alluvium, and fine alluvium that formed roughly 7 to 0 million years ago. Gravels like these concentrate whatever survives the river: agate, jasper, and other tough silica typically show up as rounded, waxy stones.

Mapped unit: Upper Santa Fe Group
Age: 7–0 Ma (Late Miocene to Middle Pleistocene)
Rock types: conglomerate sandstone, coarse alluvium, and fine alluvium
Elevation: 4,300 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 Derry

Best months: September to May. Typical highs run 97°F in midsummer and 58°F in midwinter, with winter lows near 28°F. Summer heat here is intense, so carry more water than you think you need and work the early morning.

Climate normals: NOAA 1991-2020 monthlies, CABALLO DAM station (8 mi away).

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

Rockhound State Park — Collection rules
BLM New Mexico
New Mexico Bureau of Geology and Mineral Resources
Community submissions reviewed against published agency rules

Found at Derry

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

Chert Encyclopedia →

Nearby rockhounding spots

Other rockhounding spots within driving distance of Derry.

Across the state line from Derry

Derry is close enough to the New Mexico border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.

General AreaEl Paso County, Texas · 76 mi awayGarnet, Mica, Pink Serpentine

Derry FAQ

Where is Derry?+

Derry is in Sierra County, New Mexico, at 32.78832, -107.25309. Nearest road: Lost Hill.

What rocks and minerals can you find at Derry?+

Derry is reported to produce Chert.

Is collecting allowed at Derry?+

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. Always confirm current rules with the managing agency before a trip.

What tools should I bring to Derry?+

Most agate and jasper is surface float: bring a spray bottle, a pick or small shovel, and a sturdy bag. Wet stones show their banding and translucence.

When is the best time to visit Derry?+

The most comfortable months at Derry are September to May. Summer heat here is intense, so carry more water than you think you need and work the early morning.

How do I get to Derry?+

Open the directions link to navigate to 32.78832, -107.25309 in Google Maps. The nearest road is Lost Hill.

More rockhounding in New Mexico

See all 119 New Mexico spots →

Open Derry on the map

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