Where to Find Opal in South Dakota: 4 Mapped Sites
South Dakota has 4 documented sites where opal have been reported, and the best-known are Mission, Little Eagle, and Mobridge. Every site is mapped below with GPS coordinates and links to a full report of access and what's been found there. 4 of the 4 sites are on public-access land.
Last updated: — data compiled by the Rockhounding.org Research Team · methodology
Opal Map: South Dakota
All 4 opal sites in South Dakota. Click a pin for the full site report.
Where Opal Are Found in South Dakota
Opal precipitates from silica-rich groundwater in volcanic ash beds and weathered rhyolite, and famously replaces buried wood. Look along seams and cavities in altered volcanic ground.
The richest reported sites in South Dakota: Mission, Little Eagle, Mobridge, Mound City.
Of the 4 sites, 4 are public access. Check each site report for current land status before you go.
All Opal Sites in South Dakota
- Mission — Public Access
- Little Eagle — Public Access
- Mobridge — Public Access
- Mound City — Public Access
How to Identify Opal
Opal is hardened silica gel: hardness only 5.5–6.5, waxy-to-pearly luster, conchoidal fracture, and noticeably lighter than quartz. Precious opal flashes shifting spectral color; common opal is milky, honey, or green without fire. Field-check suspect seams with a flashlight from behind — opal transmits a soft glow. Freshly dug opal can craze as it dries, so keep finds damp.
Not sure what you found? Try our identification guide →Frequently Asked Questions
Where can I find opal in South Dakota?
South Dakota has 4 mapped sites where opal have been reported. The best-known are Mission, Little Eagle, and Mobridge. Each listing on the map above includes GPS coordinates, access type, and what has been found there.
How many opal sites are mapped in South Dakota?
We have 4 documented opal sites in South Dakota, compiled from community submissions and published locality records and reviewed by the Rockhounding.org Research Team.
Is it legal to collect opal in South Dakota?
Casual collecting is generally allowed on BLM and National Forest land for personal, non-commercial use — the standard BLM limit is 25 lbs per day plus one specimen. National parks, monuments, and many state parks prohibit collecting, and private land always requires the owner's permission. Check the site report for each location and verify current land status before you dig.
How do I identify opal?
Opal is hardened silica gel: hardness only 5.5–6.5, waxy-to-pearly luster, conchoidal fracture, and noticeably lighter than quartz. Precious opal flashes shifting spectral color; common opal is milky, honey, or green without fire. Field-check suspect seams with a flashlight from behind — opal transmits a soft glow. Freshly dug opal can craze as it dries, so keep finds damp.
What should I bring to collect opal?
The basics: a rock hammer, safety glasses, gloves, a bucket or padded bag for specimens, and a GPS app with the coordinates from this page. Add a spray bottle — wetting a stone makes color and banding far easier to judge in the field.
⚠️ Always verify current regulations, weather conditions, and access requirements before visiting any location. Information provided is based on community submissions and may not be current or accurate.
Data: community submissions — reviewed and approved by the Rockhounding.org Research Team. Always verify current land status, regulations, and access before visiting any site.