Diamond Hill Park, Cumberland: Amethyst & Quartz Rockhounding in Providence County, Rhode Island

Public accessBest spot3 mineralsProvidence County, Rhode IslandUpdated July 2026

Minerals reported: 3
Elevation: 250 ft
Best months: March to November

Diamond Hill is a massive white quartz outcrop with a 350-foot vertical face, historically Rhode Island's most famous locality for milky and smoky quartz and the amethyst that gave the hill its name. The state transferred the land to the Town of Cumberland in 1997, and it is now a 373-acre public town park with the quartz ledge as its centerpiece. Loose quartz litters the base of the outcrop, and the hill sits at the center of Cumberland's mineral country near the only known outcrop of cumberlandite, the state rock. Reported finds include amethyst, quartz, smoky quartz. Below: coordinates, access notes, nearby spots, and trip-planning links.

Plan your visit

Generally open to casual rockhounding

County: Providence County
State: Rhode Island
Postcode: 02864
Coordinates: 41.97402, -71.34606

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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.

Access note: Cumberland town park, open to the public. Surface collecting of loose quartz float is a long tradition here, but this is a managed park: no hammering the main outcrop, no digging, and check current Town of Cumberland Parks rules before collecting. Treat it as a look-and-surface-pick site rather than a quarry.

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 Hill Park, Cumberland

38°J

40°F

48°M

60°A

70°M

79°J

84°J

83°A

76°S

64°O

54°N

43°D

Comfortable months (45 to 90°F highs)

Best months: March to November. Typical highs run 84°F in midsummer and 38°F in midwinter, with winter lows near 19°F.

Climate normals: NOAA 1991-2020 monthlies, WOONSOCKET station (8 mi away).

Geology at Diamond Hill Park, Cumberland

This spot sits on Pondville Conglomerate, mapped as conglomerate and arkose that formed roughly 325 to 300 million years ago. Sedimentary rock like this erodes unevenly, so the most productive collecting is typically along fresh cuts, badland slopes, and active drainages.

Mapped unit: Pondville Conglomerate
Age: 325–300 Ma (Pennsylvanian)
Rock types: conglomerate and arkose
Elevation: 250 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.

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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.

Rhode Island Geological Survey
Rhode Island DEM park rules
Community submissions reviewed against published agency rules

Found at Diamond Hill Park, Cumberland

Each name 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 Diamond Hill Park, Cumberland.

Across the state line from Diamond Hill Park, Cumberland

Diamond Hill Park, Cumberland is close enough to the Rhode Island border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.

MiddlesboroughPlymouth County, Massachusetts · 25 mi awayAgate, Chalcedony
CohassetNorfolk County, Massachusetts · 34 mi awayJasper, Epidote
Bolton Lime QuarryWorcester County, Massachusetts · 34 mi awayScapolite
MaldenMiddlesex County, Massachusetts · 35 mi awayNovaculite
MarshfieldPlymouth County, Massachusetts · 36 mi awayJasper
NahantEssex County, Massachusetts · 38 mi awayJasper, Epidote, Prehnite

Diamond Hill Park, Cumberland FAQ

Where is Diamond Hill Park, Cumberland?+

Diamond Hill Park, Cumberland is in Providence County, Rhode Island, at 41.97402, -71.34606.

What rocks and minerals can you find at Diamond Hill Park, Cumberland?+

Diamond Hill Park, Cumberland is reported to produce Amethyst, Quartz, Smoky Quartz.

Is collecting allowed at Diamond Hill Park, Cumberland?+

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 Diamond Hill Park, Cumberland?+

A rock hammer, a small pry bar, gloves, and safety glasses cover most crystal ground. A screen helps in loose pocket soil, and newspaper protects points on the way out.

When is the best time to visit Diamond Hill Park, Cumberland?+

The most comfortable months at Diamond Hill Park, Cumberland are March to November.

How do I get to Diamond Hill Park, Cumberland?+

Open the directions link to navigate to 41.97402, -71.34606 in Google Maps. Some spots are remote, so check road conditions before driving out.

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