Diamond Mountain Mining: Garnet & Epidote Rockhounding in Herkimer County, New York

Plan your visit

Pay-to-dig site

County

Herkimer County

State

New York

Nearest road

NY 5S

Postcode

13365

Coordinates

43.01500, -74.87400

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

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.

Best time to visit Diamond Mountain Mining

Comfortable months (45 to 90°F highs)

Best months: April to November. Typical highs run 82°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 (3 mi away), adjusted for elevation.

Geology at Diamond Mountain Mining

This spot sits on Trenton and Black River Groups, undivided, mapped as limestone that formed roughly 470 to 460 million years ago. Carbonate rock like this dissolves and weathers readily, so fresh road cuts, quarries, and creek exposures are typically the most productive ground.

Mapped unit

Trenton and Black River Groups, undivided

Age

470–460 Ma (Middle Ordovician)

Rock types

limestone

Elevation

640 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.

• New York State Museum, Geological Survey
• NYS DEC land use rules
• Herkimer Diamond Mines
• Community submissions reviewed against published agency rules