East Granby Quarry: Datolite & Aragonite Rockhounding in Capitol Planning Region, Connecticut

Plan your visit

Generally open to casual rockhounding

County

Capitol Planning Region

State

Connecticut

Nearest road

South Main Street

Postcode

06026

Coordinates

41.93611, -72.73999

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.

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 East Granby Quarry

Comfortable months (45 to 90°F highs)

Best months: March to November. Typical highs run 85°F in midsummer and 35°F in midwinter, with winter lows near 19°F.

Climate normals: NOAA 1991-2020 monthlies, HARTFORD-BRADLEY INTL AP station (3 mi away).

Geology at East Granby Quarry

This spot sits on Holyoke Basalt, mapped as basalt and gabbro that formed roughly 200 to 175 million years ago. Volcanic ground like this weathers into rocky slopes and float, and fresh exposures in cuts and drainages are usually the most productive places to look.

Mapped unit

Holyoke Basalt

Age

200–175 Ma (Early Jurassic)

Rock types

basalt and gabbro

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.

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.

• Connecticut Geological Survey
• CT DEEP state land rules
• Community submissions reviewed against published agency rules