Philadelphia: Agate & Petrified Wood Rockhounding in Delaware County, Pennsylvania

Plan your visit

Generally open to casual rockhounding

County

Delaware County

State

Pennsylvania

Nearest road

Boy Scout Bridge

Postcode

19080

Coordinates

40.01301, -75.38954

Coordinates are approximate. Confirm the exact ground in the RockHoundR app, where land overlays show which agency manages the area.

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.

Best time to visit Philadelphia

Comfortable months (45 to 90°F highs)

Best months: March to December. Typical highs run 88°F in midsummer and 41°F in midwinter, with winter lows near 22°F.

Climate normals: NOAA 1991-2020 monthlies, NORRISTOWN station (7 mi away), adjusted for elevation.

Geology at Philadelphia

This spot sits on Felsic gneiss, mapped as gneiss that formed roughly 4600 to 540 million years ago. Metamorphic rock like this weathers into resistant float, and minerals that survive transport typically concentrate in nearby drainages.

Mapped unit

Felsic gneiss

Age

4600–540 Ma (Precambrian)

Rock types

gneiss

Elevation

270 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.

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.

• Pennsylvania Geological Survey
• DCNR state park and state forest rules
• Allegheny National Forest
• Community submissions reviewed against published agency rules