Agate Beach Park: Unakite & Chert Rockhounding in Houghton County, Michigan

Plan your visit

Generally open to casual rockhounding

County

Houghton County

State

Michigan

Coordinates

47.03993, -88.92569

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 Agate Beach Park

Comfortable months (45 to 90°F highs)

Best months: April to October. Typical highs run 77°F in midsummer and 26°F in midwinter, with winter lows near 13°F.

Climate normals: NOAA 1991-2020 monthlies, GREENLAND 6N station (14 mi away), adjusted for elevation.

Geology at Agate Beach Park

This spot sits on Oronto Group; Freda Sandstone, mapped as shale, siltstone, and arkose that formed roughly 1600 to 1000 million years ago. Tough silica like agate, jasper, and chert typically weathers out of beds like these and collects as float in drainages and on deflation surfaces.

Mapped unit

Oronto Group; Freda Sandstone

Age

1600–1000 Ma (Mesoproterozoic)

Rock types

shale, siltstone, and arkose

Elevation

590 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.

State guidance last verified: April 1, 2026

• Michigan DNR, Rockhounding rules
• Michigan Geological Survey
• Isle Royale National Park, Rules
• Community submissions reviewed against published agency rules