Tepee Canyon

Tepee Canyon (also called Teepee Canyon, and mapped by Mindat under "Hell Canyon") sits about 18 miles west of Custer, South Dakota, off US-16, roughly 2 miles west of Jewel Cave National Monument.[1][2] It's the bedrock source of the famous Fairburn agate — the banded, fortification-pattern agates found loose in gravels east of the Black Hills actually originate in chert nodules in the Minnelusa Formation exposed here.[2] This is genuine hardrock collecting: agate nodules are locked in tough limestone, so you're breaking rock, not just picking up float. A real, worthwhile stop for anyone chasing Black Hills agate, with the caveat that it's physical work with hand tools.

From Custer, SD, take US-16/Mt. Rushmore Rd. west about 17 miles; after a long descent, turn onto Forest Service Road 458, then another 0.8 mile to FS Road 456.[2] Both are seasonal Forest Service roads, closed November 15 – May 15.[2]

This is hardrock work — breaking agate nodules out of limestone matrix with a rock hammer, chisels, and a pick axe. Bring buckets, a backpack, water, and snacks; there's no shortcut around the physical effort.[2] Black Hills National Forest allows surface collection of rocks and minerals for personal use without a permit, but its general rule specifies surface collection only, with no digging or excavating[3] — worth confirming with the Hell Canyon Ranger District whether nodule-breaking at Tepee Canyon is treated as surface collecting or falls under a different rule, given the hardrock nature of the work described by collectors.

Tepee Canyon is public land within Black Hills National Forest, managed by the Hell Canyon Ranger District.[1][3] Access roads are seasonal (closed mid-November through mid-May). Standard Forest Service rockhounding rules apply — no permit needed for hand-tool surface collection, but confirm current specifics with the Ranger District given the nodule-breaking method commonly described here. No fossil collecting is permitted on National Forest land regardless.[3]