Panoche Hills, about 13 miles west of I-5, combines wide BLM badlands, fossil-rich Cretaceous layers, and colorful dry washes with the bonus of a nearby soak at Mercey Hot Springs. The landscape feels remote yet is within easy driving distance of San Jose (about two hours) and Los Banos (about one hour).

From mid-April to mid-October, vehicle access is usually restricted to reduce wildfire risk and protect sensitive species such as the blunt-nosed leopard lizard. During this seasonal closure, the area remains open for hiking, biking, and horseback riding unless further fire restrictions are in place. When the access gate is locked, parking is available outside the entrance, and the area can still be reached on foot.

Rockhounding at Panoche Hills and Mercey Hot Springs

Panoche Hills is known for dry-wash rockhounding on BLM land.

Jasper is the most common find, usually in reds, yellows, and browns, ranging from half an inch to two inches in size. Gravel bars and inside bends of washes are the best places to look.

Agate and quartz are less common but can often be spotted by their glassy shine when held up to the light.

Serpentine also appears in shades of green to blue-green, sometimes with a smooth, waxy texture typical of Central California.

The hills are also important for their geologic history. They were formed from Cretaceous marine sediments 66–100 million years ago. Fossils of mosasaurs, plesiosaurs, marine turtles, and algae have been reported. Collecting vertebrate fossils requires a permit and is reserved for scientific study, but their presence adds to the sense of history in the area.

Mercey Hot Springs, located nearby, has a dry wash on private resort land open for light surface collecting. Only the wash itself may be searched, and digging tools are not allowed. In this wash, collectors often find small jasper pebbles, pieces of milky or translucent quartz, occasional green stones that resemble jade, and rare tiny chips of petrified wood that have already loosened from the gravel.

Both on public land and at the resort, collectors must follow the rules: reasonable amounts only, hand tools on BLM land, and surface collecting only in the resort wash.

Panoche Hills and Mercey Hot Springs together make a rewarding loop for both collecting and relaxing.

Soaking: At Mercey, geothermal water emerges at about 112°F. Outdoor tubs are kept around 100–104°F, and a dry sauna is also available.

Stargazing: The area has very dark skies. On clear nights, the Milky Way is visible. Winter nights can drop into the 40s–50s°F, while spring and fall evenings are usually in the 60s–70s°F, so bring warm layers.

Wildlife: Hawks, owls, quail, and rabbits are often seen, especially at sunrise and sunset.

Easy walks: Short gravel paths and gentle hills surround the resort, making it simple to explore between activities.

Mercey Hot Springs makes a great base with soaking included. The resort offers rustic cabins, tent camping, and RV sites (back‑in, small‑load hookups, no electric heaters or A/C).

It's quiet, historic, and about 13 miles west of I‑5 on County Road J1.