Medora: Agate & Chalcedony Rockhounding in Billings County, North Dakota

Permission requiredBest spot3 mineralsBillings County, North DakotaUpdated July 2026

Minerals reported: 3
Elevation: 2,590 ft
Best months: April to October

Medora sits in the badlands of Billings County, ringed by the Little Missouri National Grassland where the Forest Service permits casual collection of petrified wood, agate, and chalcedony. The surrounding Bullion Creek and Sentinel Butte formations weather out silicified wood and chalcedony across the buttes and draws. Collecting is prohibited within the adjacent Theodore Roosevelt National Park, so the grassland tracts outside the park boundary are the legal ground. Reported finds include agate, chalcedony, silicified wood. Below: coordinates, access notes, nearby spots, and trip-planning links.

Plan your visit

Permission required before collecting

County: Billings County
State: North Dakota
Nearest road: I 94
Postcode: 58645
Coordinates: 46.92326, -103.49210

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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

Permission required before collecting

Requires landowner or agency permission before any collecting. Do not enter without explicit authorization.

Access note: Legal collecting is on the Little Missouri National Grassland (Medora Ranger District) outside the Theodore Roosevelt National Park boundary; USFS casual-collecting rules apply (personal use, hand tools, no vertebrate fossils). Land immediately around the town of Medora is a mix of private and park; get permission on private parcels and take nothing inside the national park.

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 Medora

26°J

31°F

43°M

54°A

66°M

76°J

84°J

84°A

73°S

56°O

41°N

30°D

Comfortable months (45 to 90°F highs)

Best months: April to October. Typical highs run 84°F in midsummer and 26°F in midwinter, with winter lows near 2°F.

Climate normals: NOAA 1991-2020 monthlies, MEDORA station (2 mi away), adjusted for elevation.

Geology at Medora

This spot sits on Bullion Creek Formation, mapped as claystone and siltstone that formed roughly 66 to 56 million years ago. Sedimentary beds like these are the typical host for petrified and silicified wood, which weathers out as durable float on slopes and in washes.

Mapped unit: Bullion Creek Formation
Age: 66–56 Ma (Paleocene)
Rock types: claystone and siltstone
Elevation: 2,590 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.

Today's weather

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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.

North Dakota Geological Survey
Dakota Prairie Grasslands
North Dakota Parks and Recreation rules
Community submissions reviewed against published agency rules

Found at Medora

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 Medora.

DickinsonStark County, North Dakota · 38 mi awayAgate, Chalcedony
Little Missouri RiverMcKenzie County, North Dakota · 42 mi awayMontana Moss Agate, Jasper, Agatized Wood
Lynch QuarryDunn County, North Dakota · 51 mi awayKnife River Flint
RichardtonStark County, North Dakota · 56 mi awayAgate, Chalcedony, Agatized Wood
Watford CityMcKenzie County, North Dakota · 62 mi awaySelenite
Hettinger CountyHettinger County, North Dakota · 63 mi awayAgate, Chalcedony, Silicified Wood
HettingerAdams County, North Dakota · 67 mi awayAgatized Wood
KilldeerDunn County, North Dakota · 69 mi awayKnife River Flint

Across the state line from Medora

Medora is close enough to the North Dakota border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.

GlendiveDawson County, Montana · 57 mi awayAgate, Jasper, Moss Opal
Yellowstone River - Black Bridge Boat LaunchDawson County, Montana · 59 mi awayMontana Moss Agate, Petrified Wood, Jasper
Sand CreekDawson County, Montana · 63 mi awayMontana Agate
Cracker Box CreekDawson County, Montana · 67 mi awayMontana Agate
Hatchet CreekPrairie County, Montana · 75 mi awayMontana Agate
FallonPrairie County, Montana · 75 mi awayMontana Agate

Medora FAQ

Where is Medora?+

Medora is in Billings County, North Dakota, at 46.92326, -103.49210. Nearest road: I 94.

What rocks and minerals can you find at Medora?+

Medora is reported to produce Agate, Chalcedony, Silicified Wood.

Is collecting allowed at Medora?+

Permission required before collecting. Requires landowner or agency permission before any collecting. Do not enter without explicit authorization. Always confirm current rules with the managing agency before a trip.

What tools should I bring to Medora?+

A rock hammer, sturdy gloves, and a padded bag cover petrified wood hunting. Most pieces are surface float, so walking slopes and washes beats digging.

When is the best time to visit Medora?+

The most comfortable months at Medora are April to October.

How do I get to Medora?+

Open the directions link to navigate to 46.92326, -103.49210 in Google Maps. The nearest road is I 94.

More rockhounding in North Dakota

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