There are lots of directions and maps that outline McDermitt rockhounding. It is really a wonderful place to visit. The area is an ancient caldera that sunk and filled with water, grew trees and lake plants and creatures, was covered with ash and lava, and subsequently invaded by replacement chemicals that formed agates, jaspers, fossils, petrified wood, minerals and every sort of thing in between.
You can see the outline of the eroded caldera to the left of McDermitt on the map below. The rock hounding areas are typically in the center of this circular valley, but there are interesting things all over the area.
One area has deep green deposits of petrified algae. Some of these are giant encrusted masses that are softer and not suitable for lapidary work
Harder pieces polish well and often contain mottled patterns of white and cream colored agates. I use this large piece as a coffee coaster.
There is one area with picture stone. Someone stuck dynamite in a couple of outcrop places and exposed several pits of this material. It takes some effort to get it cut and polished, but some pieces have dramatic scenery in the wonderful embedded lines of rock layers. There are big rattle snakes amidst this stuff, so watch your step.
On the edges of the caldera you can find banded rhyolites and many other mineralized forms of rock. The Carldera rock shop in McDermitt is a good stopping place to see all that the valley has to offer.
There are hillsides of agates of various colors and densities. Carnival agate has browns, white, green and black. Some of these agates are good for slabs while others are checked and can be tumbled. The size of agate chunks can be from ones buried in bed rock the size of a VW to portable bowling ball sizes. The the desert floor is littered with marbles!
If the only place you looked for rocks was on the road, you could still have a truck full.
There's a rock out there someplace with a rock hammer left atop as an ornament. It's a nice Estwing, so keep your eyes open if you visit.
There are some gem quality rocks in this region including this banded jasper. Some of these digs are under claim, so take care to get permissions where there are markings or property lines Most of he area is BLM, but there are mining claims all around.
If you are looking for a map and a guide of what you will find in the area, make a stop at the Caldera Rock Shop. They have bulk rock for sale as well as polished specimens. These folks have claims and can tell you where to find stuff.
There are places where you can find petrified wood that is hard and polishes well. One has to dig to find limbs and chunks of hard wood. Some require a backhoe and crane!
Opalized wood is very common and disintegrates into a pile of shards. I put a piece of beautiful yellow wood in my pocket and when I got back to camp it was crumbs.
There is much to explore in this area. The wildlife and wildflowers are plentiful accented by the rock float!
The BLM land extends over the Oregon-Nevada border so you could be in either state depending on where you meander. There are obsidian chips on different overlooks so the presence of native peoples is clear. Plan on several days stay to thoroughly assess what McDermitt-west has to offer. Watch for rattlesnakes!