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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.

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Every chalcedony spot we track in Wyoming

Standout chalcedony spots in Wyoming

Hand-picked from the full list above, with the reason each one earns a trip.

Best counties for chalcedony in Wyoming

Ranked by the number of mapped chalcedony spots. County links open the full rockhounding page for that county.

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

Where can you find chalcedony in Wyoming?+
The mapped spots concentrate in Fremont County, Sweetwater County, and Natrona County. Known collecting areas include Sweetwater River gravels (Fremont County), Hartville uplift (Platte County), and Hat Six area (Natrona County). Every spot on this page is on the map, and each spot's own page has its coordinates and access notes.
How many chalcedony spots are mapped in Wyoming?+
22 spots across 11 counties. The RockHoundR app keeps the same spots on an offline map with public land overlays, geology layers, and your saved finds.
Is it legal to collect chalcedony in Wyoming?+
Hand collecting of common rocks and minerals in small amounts for personal use is generally allowed on BLM and U.S. Forest Service land, with limits set by the local field office. National parks, most state parks, and tribal land are closed to collecting. 17 of the 22 mapped spots here sit on land marked public. Always confirm current rules with the managing agency before you dig.

Where else to find chalcedony

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.

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