Sweetwater Country (central Wyoming)
Sweetwater agate, moss agate, and jasper across the Granite Mountains and the Sweetwater River drainage. BLM ground with long, lonely roads.
Rockhounding in Wyoming
Updated July 2026
82 mapped spots across 19 counties. Wyoming is a good state for agate, jade, petrified wood, and fossil fish. The Sweetwater agate fields, Wiggins Fork petrified wood area, Wyoming jade country, and Kemmerer quarries are the main anchors.
Where is the best rockhounding in Wyoming?
The best rockhounding in Wyoming is at Sweetwater River in Fremont County (agate), Atlantic City in Fremont County (agate, chalcedony), and Warm Springs in Fremont County (agate, chalcedony). In total, 82 mapped collecting spots across 19 counties produce agate, jasper, and chalcedony, each listed below with coordinates and land access notes.
Wyoming rockhounding photos
Representative spot and material photos from locations in this state, shown where verified public image records are available.
Map showing 82 rockhounding spots in Wyoming
Top minerals found in Wyoming
Counts reflect how many spots in this list mention each mineral.
- Agate23
- Jasper22
- Chalcedony21
- Quartz11
- Silicified Wood10
- Gypsum8
- Gold6
- Malachite6
- Chert5
- Copper5
- Opalized Wood5
- Petrified Wood5
Notable areas: Sweetwater agate, Wyoming jade, Wiggins Fork petrified wood, and Tin Cup quartz are common Wyoming targets.
Geology behind Wyoming rockhounding
Wyoming is half BLM by area. Its collecting hot spots reflect Eocene to Miocene lake-and-volcanic geology: the Sweetwater River basin's agate-and-jasper gravels (Granite Mountains source), the Wiggins Fork and Absaroka Mountains' opalized and silicified wood, the Granite Mountains' nephrite jade, and the Green River Formation's fossil fish near Kemmerer (commercial quarries plus public quarry days).
Best regions to focus your search
Wyoming jade belt (Granite Mountains, Lander area)
Nephrite jade as float and in-place. The hunt is patient — most surface material was picked over in the boom years, but the area still gives up jade after washouts.
Wiggins Fork / Absaroka petrified wood
Permineralized wood in Eocene tuffs of the Absaroka volcanic province. Remote — high country with grizzly habitat. Travel in groups.
Green River Formation (Kemmerer)
Fossil fish at commercial quarries (American Fossil, Ulrich's, Warfield, Tynsky's) on public quarry days. Knightia is the typical catch.
Best season
June–September. Wyoming's high desert is cold and wind-scoured the rest of the year. Kemmerer quarries run May through October.
What to bring
Wind shell, bear spray (for the Absaroka country), full-size spare and high-clearance vehicle, water for the day, paper map. For Kemmerer fossil quarries: small chisels and a flat-blade screwdriver — the quarries provide most tools.
Local collecting history
Jade was designated Wyoming's state gem in 1967. The Sweetwater agate fields had their first big rush in the 1930s and 1940s, when collectors fanned across the Granite Mountains by horseback. Wiggins Fork petrified wood has been worked since the 1950s.
Rockhounding near major Wyoming cities
Day-trip range. Each section lists the closest mapped rockhounding spots within about 150 miles of the city — most are inside a 2 to 3 hour drive.
Rockhounding near Cheyenne
See all →6 closest spots to Cheyenne, WY.
- Copper King MineLaramie County · Barite, Copper19 mi24 min drive
- Chugwater CreekLaramie County · Bloodstone37 mi46 min drive
- LaramieAlbany County · Gypsum39 mi49 min drive
- Diamond PeakLarimer County · Diamond40 mi50 min drive
- Red ButtesAlbany County · Gypsum42 mi52 min drive
- Sportman LakeAlbany County · Gypsum42 mi52 min drive
Rockhounding near Casper
See all →6 closest spots to Casper, WY.
- CasperNatrona County · Agate, Alabaster1 mi2 min drive
- CasperNatrona County · Beryl, Muscovite11 mi14 min drive
- Poison Spider CreekNatrona County · Agate, Chalcedony13 mi16 min drive
- Deer Creek Canyon MineConverse County · Chromite19 mi24 min drive
- Box Elder CanyonConverse County · Geode, Quartz28 mi35 min drive
- Moss Agate HillConverse County · Moss Agate, Chalcedony35 mi44 min drive
Rockhounding near Rock Springs
See all →6 closest spots to Rock Springs, WY.
- Rock SpringsSweetwater County · Agate, Chalcedony3 mi4 min drive
- Sweetwater CountySweetwater County · Agate, Chalcedony15 mi19 min drive
- Green RiverSweetwater County · Agate, Chalcedony27 mi33 min drive
- Steamboat MountainSweetwater County · Agate, Chalcedony29 mi36 min drive
- Bitter CreekSweetwater County · Tschermigite34 mi43 min drive
- Eden ValleySweetwater County · Silicified Wood35 mi44 min drive
Neighboring states with rockhounding
Geology rarely respects state borders. These states share mapped rockhounding country with Wyoming — useful when Wyoming is the start, not the whole trip. Each card links to the closest county across the line.
Rockhounding by county in Wyoming
County pages are linked once we have at least 3 mapped spots for a focused guide with coordinates, mineral notes, and nearby spots.
- Fremont County16 spotsTop: Agate, Jasper, Chalcedony
- Sweetwater County10 spotsTop: Agate, Chalcedony, Jasper
- Carbon County8 spotsTop: Opalized Wood, Autunite, Azurite
- Albany County6 spotsTop: Gypsum, Agate, Barite
- Big Horn County6 spotsTop: Fossils, Gastroliths, Gypsum
- Natrona County6 spotsTop: Agate, Chalcedony, Alabaster
- Converse County4 spotsTop: Chalcedony, Chalcopyrite, Chromite
- Park County4 spotsTop: Agate, Anhydrite, Azurite
- Platte County4 spotsTop: Agate, Arsenopyrite, Barite
- Crook County3 spotsTop: Gold, Malachite, Azurite
- Lincoln County2 spotsTop: Chalcedony, Chert, Jasper
Top picks in Wyoming
10 best spotsHand-picked standouts from the Wyoming list, chosen for unusual mineralogy, documented public access, or both. Each card links to coordinates, access notes, and what to look for.
Top pickSweetwater River
PermissionFremont County
Sweetwater agate is Wyoming's signature agate, and the Sweetwater River drainage is the classic field area tied to the Granite Mountains source terrain.
Agate
Top pickAtlantic City
PublicFremont County
Atlantic City sits in the South Pass country, where Wyoming's gold-mining history overlaps with the central Wyoming jade and agate belt.
Agate, Chalcedony, Gold, Nephrite Jade
Top pickWarm Springs
PublicFremont County
Warm Springs is a strong Granite Mountains-area pick because it combines Wyoming jade targets with agate, jasper, chalcedony, quartz, and silicified wood in one public-land collecting corridor.
Agate, Chalcedony, Jasper, Jade
Top pickKirwin Mine
PublicPark County
Kirwin is the strongest metallic-mineral contrast to Wyoming's agate and wood localities, with USGS work documenting the district's copper, gold, lead, zinc, molybdenum, and silver mineralization.
Azurite, Barite, Chalcopyrite, Cuprite
Top pickEden Valley
PublicSweetwater County
Eden Valley is the Wyoming benchmark for silicified and agatized wood, with Mindat records tying petrified wood to Eden Valley and the Blue Forest area.
Silicified Wood
Top pickWamsutter
PublicSweetwater County
Wamsutter is the practical Wyoming stop for dark fossiliferous lapidary material sold as Turritella agate, more accurately tied to silicified Green River Formation gastropods.
Turritella Agate
Top pickKemmerer
PublicLincoln County
Kemmerer anchors the western Green River Formation belt, where public-land outcrops and gravels can yield chert, chalcedony, jasper, silicified wood, and fossiliferous lapidary stone.
Turritella Agate, Chalcedony, Chert, Jasper
Top pickLaramie Mountains
PublicAlbany County
The Laramie Mountains add a southeastern public-land agate, chalcedony, and jasper stop to a Wyoming list otherwise dominated by Sweetwater and Green River Basin material.
Agate, Chalcedony, Jasper
Top pickSeminoe Reservoir
PublicCarbon County
Seminoe Reservoir represents the Seminoe Mountains side of Wyoming's jade and lapidary-rock story, with WSGS noting silicified banded iron formation from the Seminoe Mountains alongside the state's better-known jade resources.
Jade
Top pickHartville
PublicPlatte County
Hartville is the southeastern Wyoming choice for Guernsey Limestone chalcedony, including moss agate, dendritic agate, stalactitic agate, and youngite noted by WSGS.
Agate, Moss Agate, Chalcedony
Every rockhounding spot in Wyoming
Sorted by county. Tap coordinates to open in Google Maps, or open RockHoundR for the full map view with land overlays and weather.
Wyoming rockhounding FAQ
Is rockhounding legal in Wyoming?+
Yes on BLM and USFS land under the BLM 25 lb/day, 250 lb/year rule. Yellowstone, Grand Teton, Fossil Butte National Monument, Wyoming State Parks, and the Wind River Reservation are closed. Vertebrate fossils are federally protected on public land.
Where can I find Wyoming jade?+
The classic ground is the Granite Mountains and Sweetwater drainage in central Wyoming, on BLM land south of Lander. Hand picking after spring washouts is the typical strategy — most easily accessible surface material was picked over decades ago.
How do the Kemmerer fossil fish quarries work?+
Several private quarries, including American Fossil, Ulrich's, Warfield, and Tynsky's, sit on the Green River Formation outside Fossil Butte National Monument. Pay a daily rate, split shale, and keep what you find, usually Knightia and sometimes Mioplosus, Diplomystus, or rarer species under each quarry's rules.
Can I keep Sweetwater agate I pick off BLM land?+
Yes. Sweetwater agate is a common semiprecious gemstone covered under the BLM 25 lb/day, 250 lb/year rule. Avoid posted claims and don't dig pits — surface picking is the norm.
What rocks and minerals can you find in Wyoming?+
Common targets include Sweetwater agate, Wyoming jade, petrified wood (Wiggins Fork, Eden Valley), Green River fossil fish (Kemmerer quarries), Youngite (calcite-on-agate from the Casper area), and Tin Cup quartz crystals.
Map every Wyoming spot in the app
Open the RockHoundR app to see Wyoming on a real map with public land overlays, weather, geology, and your saved finds.
