Harrisville State Park: Granite & Chert Rockhounding in Alcona County, Michigan
- Minerals reported
- 8
- Elevation
- 630 ft
- Best months
- April to October
Harrisville State Park is a mapped rockhounding spot in Alcona County, Michigan. Reported finds include granite, chert, quartz, chain coral, horn coral, and more. Below: coordinates, access notes, nearby spots, and trip-planning links.
Plan your visit
Pay-to-dig site
- County
- Alcona County
- State
- Michigan
- Postcode
- 48740
- Coordinates
- 44.64750, -83.29764
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 Harrisville State Park
Comfortable months (45 to 90°F highs)
Best months: April to October. Typical highs run 73°F in midsummer and 26°F in midwinter, with winter lows near 13°F.
Climate normals: NOAA 1991-2020 monthlies, HARRISVILLE SP station (0 mi away).
Geology at Harrisville State Park
This spot sits on Sunbury Shale, mapped as black shale that formed roughly 420 to 325 million years ago. Sedimentary layers like these are where fossils are typically preserved, and fresh exposures after rain or in active cuts tend to produce best.
- Mapped unit
- Sunbury Shale
- Age
- 420–325 Ma (Devonian to Mississippian)
- Rock types
- black shale
- Elevation
- 630 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.
Today's weather
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The app shows live weather, recent rain, and a daily rockhounding score for Harrisville State Park.
Get the appSources & 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:
- Michigan DNR, Rockhounding rules
- Michigan Geological Survey
- Isle Royale National Park, Rules
- Community submissions reviewed against published agency rules
Found at Harrisville State Park
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 Harrisville State Park.
- Sturgeon Point LighthouseAlcona County, Michigan · 5 mi awayGranite, Chert, Fossil
- Negwegon State ParkAlcona County, Michigan · 14 mi awayPuddingstone, Petoskey Stone, Granite
- Partridge PointAlpena County, Michigan · 26 mi awayCrinoid, Brachiopod, Horn Coral
- Tawas Point State ParkIosco County, Michigan · 28 mi awayQuartz, Granite, Gneiss
- Singing Bridge Public AccessArenac County, Michigan · 37 mi awayPetoskey Stone, Charlevoix Stone, Gneiss
- Rockport Recreation AreaAlpena County, Michigan · 39 mi awayPetoskey Stone, Fossilized Coral, Brachiopod
- Besser Natural AreaPresque Isle County, Michigan · 42 mi away
- Port Crescent State ParkHuron County, Michigan · 46 mi away
Harrisville State Park FAQ
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More rockhounding in Michigan
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