Rockhound State Park

Up to 15 pounds of rock and mineral material per person per day, for personal use. It is one of the most generous collecting allowances at any park in the United States. Mineral dealers and anyone collecting for resale are barred from collecting in the park.

Thundereggs, agate, jasper, gray perlite, onyx, crystalline rhyolite, Apache tears (obsidian) and quartz crystals. They weather out of mid-Tertiary ash-flow tuffs and lavas on the slopes of the Little Florida Mountains. Collecting is best a few days after rain, when runoff exposes fresh material.

Yes. New Mexico State Parks charges a day-use fee per vehicle, with camping billed separately. The park has 29 developed campsites, 23 of them with electric hookups, plus showers, restrooms and an RV dump station. Call 575-546-6182 for current rates.

October through April. The collecting slopes are steep, exposed and shadeless, which makes summer field work in the Chihuahuan Desert genuinely hazardous. Whatever the month, go a few days after rainfall, which washes fresh material out of the hillsides.

About 14 miles southeast of Deming, New Mexico, at 9880 Stirrup Road SE, in the Little Florida Mountains. The approach from Interstate 10 at Deming is paved the whole way via NM-11 and NM-143 and is suitable for RVs heading to the campground.

Collecting happens uphill from the campground on the slopes of the Little Florida Mountains, so expect a walk with elevation gain rather than a roadside stop. Park at the trailheads and work up. The park spans roughly 4,520 to 5,400 feet, and the productive ground is the higher, more eroded slopes.

A spherulite: a nodule with a dark outer shell of quartz, feldspar and magnetite around an agate, chalcedony or quartz core. In the field, look for roughly spherical, knobbly nodules that stand out from the surrounding volcanic rubble. You cannot tell the interior from the outside, which is why they get cut.

Yes. The park has 29 developed campsites, 23 of them with electric hookups, plus showers, restrooms, an RV dump station and group camping. That makes it a practical base for collecting over several days and for exploring the Deming area of southwest New Mexico.

It is one of the best beginner sites in the country, because collecting is not only permitted but encouraged, the 15-pound daily limit is generous, and the visitor center explains what you are likely to find. The demands are physical rather than technical: steep loose slopes, full sun and no shade.

A separate day-use unit of the park a few miles away in the Little Florida Mountains, known for scenery, hiking and a herd of Persian ibex introduced in the 1970s. Check current rules for that unit separately, since day-use areas and the main park can differ.

Reports vary widely and the pattern is consistent: those who walk uphill to the more eroded slopes and search after rain describe filling their 15 pounds without difficulty, while those who stay near the campground and picnic areas describe picking over ground that thousands of visitors have already worked. Sixty years of collecting have thinned the easy access areas, and the honest advice is that the reward here scales directly with how far up you are willing to walk.

Collectors consistently describe it as 15 pounds per person per day, which is how the park and state sources present it, and note that it applies to personal use only since mineral dealers and anyone collecting for resale are barred from collecting in the park. The practical observation people make is that 15 pounds of thundereggs and jasper is more than most visitors want to carry down a steep slope anyway.