Derry: Quartz & Chalcedony Rockhounding in Westmoreland County, Pennsylvania

Updated June 2026

Derry is a mapped rockhounding spot in Westmoreland County, Pennsylvania. Reported finds include quartz, chalcedony, jasper. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Westmoreland County
State: Pennsylvania
Nearest road: Mill Street
Postcode: 15627
Coordinates: 40.34880, -79.26809

Geology at Derry

This spot sits on Pottsville Formation, mapped as sandstone and conglomerate that formed roughly 325 to 300 million years ago. Tough silica like agate, jasper, and chert typically weathers out of beds like these and collects as float in drainages and on deflation surfaces.

Mapped unit: Pottsville Formation
Age: 325–300 Ma (Pennsylvanian)
Rock types: sandstone and conglomerate
Elevation: 1,340 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: March to December. Typical highs run 85°F in midsummer and 41°F in midwinter, with winter lows near 24°F.

Climate normals: NOAA 1991-2020 monthlies, LAUREL MTN station (11 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.

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

Found at Derry

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

Nearby rockhounding spots

Other rockhounding spots within driving distance of Derry.

Across the state line from Derry

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

Derry FAQ

Where is Derry?+

Derry is in Westmoreland County, Pennsylvania, at 40.34880, -79.26809. Nearest road: Mill Street.

What rocks and minerals can you find at Derry?+

Derry is reported to produce Quartz, Chalcedony, Jasper.

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 March to December.

How do I get to Derry?+

Open the directions link to navigate to 40.34880, -79.26809 in Google Maps. The nearest road is Mill Street.

More rockhounding in Pennsylvania

See all 88 Pennsylvania spots →

Open Derry on the map

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