Ace of Diamonds Mine: Herkimer Diamond Rockhounding in Herkimer County, New York

Quick details

Access

Paid / fee dig

County

Herkimer County

State

New York

Nearest road

New York State Thruway

Coordinates

43.01100, -74.97200

Geology at Ace of Diamonds Mine

This spot sits on Glacial and Alluvial Deposits, mapped as unconsolidated alluvium that formed within roughly the last 3 million years. Loose deposits like these are float-collecting ground: erosion keeps moving durable rocks and minerals into gravel bars, cutbanks, and washes.

Mapped unit

Glacial and Alluvial Deposits

Age

3 Ma to present (Quaternary)

Rock types

unconsolidated alluvium

Elevation

550 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 Ace of Diamonds Mine

Best months: April to November. Typical highs run 83°F in midsummer and 31°F in midwinter, with winter lows near 12°F.

Climate normals: NOAA 1991-2020 monthlies, LITTLE FALLS CITY RSCH station (6 mi away), adjusted for elevation.

Land & collecting status

Pay-to-dig site

This is a fee-dig location. Hours, prices, and what you can keep vary by operator. Call ahead before driving out.

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 Ace of Diamonds Mine

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

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