Sayreville: Marcasite & Pyrite Rockhounding in Middlesex County, New Jersey

Updated June 2026

Sayreville is a mapped rockhounding spot in Middlesex County, New Jersey. Reported finds include marcasite, pyrite, petrified wood. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Middlesex County
State: New Jersey
Nearest road: Bordentown Avenue
Postcode: 08879
Coordinates: 40.43869, -74.32979

Geology at Sayreville

This spot sits on Magothy Formation, mapped as sand that formed roughly 86 to 84 million years ago. Petrified wood typically travels as tough float, and worked gravels like these are exactly where weathered pieces tend to collect.

Mapped unit: Magothy Formation
Age: 86–84 Ma (Late Cretaceous)
Rock types: sand
Elevation: 40 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 Sayreville

Best months: March to December. Typical highs run 87°F in midsummer and 41°F in midwinter, with winter lows near 23°F.

Climate normals: NOAA 1991-2020 monthlies, NEW BRUNSWICK 3 SE station (5 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.

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

Found at Sayreville

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 Sayreville.

Across the state line from Sayreville

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

Sayreville FAQ

Where is Sayreville?+

Sayreville is in Middlesex County, New Jersey, at 40.43869, -74.32979. Nearest road: Bordentown Avenue.

What rocks and minerals can you find at Sayreville?+

Sayreville is reported to produce Marcasite, Pyrite, Petrified Wood.

Is collecting allowed at Sayreville?+

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 Sayreville?+

A rock hammer, sturdy gloves, and a padded bag cover petrified wood hunting. Most pieces are surface float, so walking slopes and washes beats digging.

When is the best time to visit Sayreville?+

The most comfortable months at Sayreville are March to December.

How do I get to Sayreville?+

Open the directions link to navigate to 40.43869, -74.32979 in Google Maps. The nearest road is Bordentown Avenue.

More rockhounding in New Jersey

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Open Sayreville on the map

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