Coal Hollow: Siderite Rockhounding in Martin County, Indiana

Quick details

Access

Public area

County

Martin County

State

Indiana

Coordinates

38.62564, -86.76539

Geology at Coal Hollow

This spot sits on Raccoon Creek Group, mapped as shale and sandstone 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

Raccoon Creek Group

Age

325–300 Ma (Pennsylvanian)

Rock types

shale and sandstone

Elevation

780 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.

Best time to visit Coal Hollow

Best months: February to November. Typical highs run 87°F in midsummer and 40°F in midwinter, with winter lows near 22°F.

Climate normals: NOAA 1991-2020 monthlies, SHOALS 8 S station (5 mi away), adjusted for elevation.

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.

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.

Sources: RockHoundR public spot dataset, app land overlays, and local agency review before each trip.

Found at Coal Hollow

Each chip opens all spots that produce that material; the encyclopedia link opens the full ID and field guide.

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