Arlington: Jasper Rockhounding in Arlington County, Virginia

Quick details

Access

Permission required

County

Arlington County

State

Virginia

Nearest road

Custis Memorial Parkway

Postcode

22209

Coordinates

38.89834, -77.09248

Geology at Arlington

This spot sits on Sykesville Formation, mapped as conglomerate that formed roughly 540 to 510 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

Sykesville Formation

Age

540–510 Ma (Early Cambrian)

Rock types

conglomerate

Elevation

200 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 Arlington

Best months: February to December. Typical highs run 88°F in midsummer and 43°F in midwinter, with winter lows near 25°F.

Climate normals: NOAA 1991-2020 monthlies, DALECARLIA RSVR station (3 mi away).

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.

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

Found at Arlington

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

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