Where to Find Chalcedony in Wyoming
Wyoming chalcedony tracks the same volcanic and sedimentary corridors that produce the state's agate. Sweetwater chalcedony, often called Sweetwater agate, is a pink-and-white banded variety from the Sweetwater River gravels in Fremont and Sublette counties. The Hartville uplift in Platte County yields white-to-cream chalcedony nodules in altered limestone, and the Powder River basin in Campbell County adds float chalcedony eroded from old volcanic terranes. The Hat Six area east of Casper produces blue chalcedony in basalt. Most surface chalcedony is small (under fist-size) and concentrated on ranch gravels.
Spot list checked against source data on April 1, 2026.
Map of 21 chalcedony collecting spots in Wyoming
Standout chalcedony spots in Wyoming
Hand-picked from the full list below, with the reason each one earns a trip.
Laramie Mountains
Albany County 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. WSGS mineral references also place the range in a broader hard-rock context, which gives the locality more geologic range than an ordinary gravel-bar agate stop.
Atlantic City
Fremont County County
Atlantic City sits in the South Pass country, where Wyoming's gold-mining history overlaps with the central Wyoming jade and agate belt. The mix of quartz, muscovite, tourmaline, jasper, chalcedony, and nephrite makes it a broader hard-rock and float locality than the single-material Sweetwater agate stops nearby.
Warm Springs
Fremont County 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. WSGS identifies jade as Wyoming's best-known gemstone and also lists agate, petrified wood, and quartz crystals among the state's important collector materials.
Kemmerer
Lincoln County 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. It is included separately from the paid fossil-fish quarries because the best free collecting value is common lapidary material on verified public parcels, not commercial quarry access.
Hartville
Platte County County
Hartville is the southeastern Wyoming choice for Guernsey Limestone chalcedony, including moss agate, dendritic agate, stalactitic agate, and youngite noted by WSGS. Its appeal is the combination of lapidary-grade silica and mining-district geology in a part of the state outside the central Sweetwater jade and agate belt.
Best counties for chalcedony in Wyoming
Ranked by the number of mapped chalcedony spots. County links open the full rockhounding page for that county.
- Fremont County6 spots
- Sweetwater County6 spots
- Natrona County2 spots
- Albany County1 spot
- Converse County1 spot
- Johnson County1 spot
- Lincoln County1 spot
- Platte County1 spot
- Uinta County1 spot
- Washakie County1 spot
Every chalcedony spot we track in Wyoming
Sorted by county. Coordinates open in Google Maps.
Before you go
Read the chalcedony identification guide so you know what a keeper looks like in the field: Chalcedony in the encyclopedia.
Chalcedony in Wyoming FAQ
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More minerals to hunt in Wyoming
Hunt chalcedony in Wyoming with the map in your pocket
RockHoundR puts these spots on an offline map with BLM and Forest Service overlays, geology layers, and a log for your finds.
