Spring and fall. We found this agate with dendrites on Agate Hill, near McDermitt.
Black dendrites are on white, tan and brown agate.
Take the dirt road toward Disaster Peak. As you turn onto the road, another dirt road goes north. Stay to the left and continue toward Disaster Peak for 4 miles. At this point, a dirt track goes up the hill to the right just east of the cattleguard. If you have a high-clearance vehicle, drive up the track 0.4 mile and park on the wide flat area at the top of the hill.