Hillsboro: Rhyolite Rockhounding in Sierra County, New Mexico

Updated June 2026

Hillsboro is a mapped rockhounding spot in Sierra County, New Mexico. Reported finds include rhyolite. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Sierra County
State: New Mexico
Nearest road: NM 152
Postcode: 88042
Coordinates: 32.91564, -107.60578

Geology at Hillsboro

This spot sits on Lower-upper middle Tertiary basaltic andesites and andesites of the Mogollon Group, mapped as andesite, basaltic andesite, and basalt that formed roughly 34 to 23 million years ago. Volcanic ground like this weathers into rocky slopes and float, and fresh exposures in cuts and drainages are usually the most productive places to look.

Mapped unit: Lower-upper middle Tertiary basaltic andesites and andesites of the Mogollon Group
Age: 34–23 Ma (Early Oligocene to Late Oligocene)
Rock types: andesite, basaltic andesite, and basalt
Elevation: 5,640 ft

Geologic mapping via Macrostrat and the underlying state geological survey maps (CC BY 4.0). Bedrock at the surface can vary within a mapped unit.

Best time to visit Hillsboro

Best months: July to May. Typical highs run 90°F in midsummer and 53°F in midwinter, with winter lows near 24°F.

Climate normals: NOAA 1991-2020 monthlies, HILLSBORO station (2 mi away), adjusted for elevation.

Land & collecting status

Generally open to casual rockhounding

Most public-tagged spots sit on BLM, U.S. Forest Service, or other federal land where reasonable hand collecting of common rocks and minerals is allowed. Confirm posted rules and active mining claims before you dig.

Public-land rules vary by agency, season, and field office. The RockHoundR app pulls live BLM, USFS, NPS, and tribal overlays so you can see exactly which agency manages the ground at this spot.

Sources & verification

Spot details combine the public RockHoundR location dataset, normalized mineral labels, agency land-status checks in the app, and community submissions. Coordinates are approximate until verified in the field.

State guidance last verified: April 1, 2026

Rockhound State Park — Collection rules
BLM New Mexico
New Mexico Bureau of Geology and Mineral Resources
Community submissions reviewed against published agency rules

Found at Hillsboro

Each chip opens all spots that produce that material; the encyclopedia link opens the full ID and field guide.

Rhyolite

Nearby rockhounding spots

Other rockhounding spots within driving distance of Hillsboro.

Hillsboro FAQ

Where is Hillsboro?+

Hillsboro is in Sierra County, New Mexico, at 32.91564, -107.60578. Nearest road: NM 152.

What rocks and minerals can you find at Hillsboro?+

Hillsboro is reported to produce Rhyolite.

Is collecting allowed at Hillsboro?+

Generally open to casual rockhounding. Most public-tagged spots sit on BLM, U.S. Forest Service, or other federal land where reasonable hand collecting of common rocks and minerals is allowed. Confirm posted rules and active mining claims before you dig. Always confirm current rules with the managing agency before a trip.

What tools should I bring to Hillsboro?+

A rock hammer, sturdy gloves, safety glasses, and a collecting bag cover the basics here. Add a spray bottle: wet rock shows color and pattern that dry rock hides.

When is the best time to visit Hillsboro?+

The most comfortable months at Hillsboro are July to May.

How do I get to Hillsboro?+

Open the directions link to navigate to 32.91564, -107.60578 in Google Maps. The nearest road is NM 152.

More rockhounding in New Mexico

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Open Hillsboro on the map

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