Rockhounding 101: Bring out the Treasure Hunter in You

There might be treasure right under your feet, you just have to know where to look.
Marcia Wendorf

Rockhounding, also known as amateur geology, is the recreational study and collecting of rocks, gems, minerals, and fossils from their natural environment.

Minerals are solid, inorganic substances that have a specific chemical composition and crystal structure that occurs naturally in pure form. Gems are precious or semiprecious minerals that can be cut and polished. Gold is neither a gem nor a mineral, it is a chemical element.

Rockhounding brings out the treasure hunter in all of us, but especially in children. It's a great way to get kids interested in geology and away from in front of a screen, and there are hundreds of local gem clubs worldwide which are a great way to meet new people.

You can make some spare cash by selling off some of your specimens, or you can even find an engagement ring for your fiancee. CNN recently reported on Washington state native Christian Liden, who was determined to find a diamond for an engagement ring for his girlfriend, Desirae.

On May 1, 2021, Linden and a friend headed to Crater of Diamonds State Park in Murfreesboro, Arkansas, with a brief stop off in Montana to try to find sapphires. On May 10, 2021, after two unsuccessful days of searching, Linden found a 2.20-carat yellow diamond. Returning home, Linden proposed to his girlfriend Desirae, and she said, "Yes".

Did you know that every U.S. state has its own state mineral? For example, the state mineral of Illinois is fluorite, while South Dakota's state mineral is rose quartz.

Rockhounding rules

You can rockhound on public land, but not at National Monuments or National Parks. The Bureau of Land Management provides guidelines on what types of specimens you can collect and how many, and it is considered bad etiquette to sell materials you have collected from public lands. You can also rockhound on private land or at paid dig sites, however, private land should only be accessed with the owner's permission.

If you go rockhounding, be sure not to damage the land, and also carry away any litter. If you camp out at the site and make a fire, be sure to properly extinguish it. The best places to look for specimens are at the bottom of cliffs, along the edges of streams and rivers, and along roadcuts where large volumes of stone have been removed.

Moh's Hardness Scale
Moh's Hardness Scale. Source: USGS/Marcia Wendorf

One of the best ways of identifying a mineral in the field is by scratching it with a known stone. A harder material will scratch a softer one. In 1822, the German Geologist Friedrich Mohs created the scale named for him which ranks minerals in hardness from 1 to 10, with talc being the softest, or 1, and diamond being the hardest, or 10.

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The basic tools you'll need to rockhound are:

  • Rock hammer or rock pick
  • Sieve or colander
  • Trowel or a small knife
  • Small broom or paintbrush
  • Spray bottle filled with water
  • Various sizes of chisels, be sure they are rated for masonry
  • Pry bar
  • Shovel, small folding shovels are convenient
  • A good pair of gloves
  • Plastic baggies or a bucket to store your finds.

You may also want a stone polisher or rock tumbler to polish up any finds you make. If you'd like to get into rockhounding, we've prepared a list for you of the best sites in the U.S. to find spectacular specimens.

Crater of Diamonds State Park, Murfreesboro, Arkansas

Crater of Diamonds State Park
Crater of Diamonds State Park. Source: Crater of Diamonds State Park

Crater of Diamonds State Park is one of the only places in the world where the public can search for diamonds. Located in Murfreesboro, Arkansas on 37 acres, the park attracts visitors from all over the world, however, admittance is limited to 800 people per day, so it's a good idea to call ahead.

Crater of Diamonds became a state park in 1972 and is made up of the eroded surface of a 95 million-year-old volcano. Any rock or mineral you find is yours to keep, and you can either rent mining tools from the park, or you can bring your own. Battery-operated or motor-driven tools are prohibited.

What you are pulling out of the ground are uncut diamonds. These look much different from the diamonds you see in jewelry, which have been cut and polished. Diamonds at the park primarily come in three colors: white, yellow, and brown. You can also find amethyst, garnet, jasper, agate, and quartz. Park staff will be happy to help you identify your finds.

To date, over 33,000 diamonds have been found since the site became a state park. These include the 40.23-carat Uncle Sam, the largest diamond ever unearthed in the U.S., the 16.37-carat Amarillo Starlight, the 15.33-carat Star of Arkansas, and the 8.52-carat Esperanza. Crater of Diamonds State Park also includes a Diamond Discovery Center, aquatic playground, walking trails, picnic sites, and campsites.

Gold Prospecting Adventure, Jamestown, CA

Gold panning
Gold panning. Source: BanksPhotos/iStock

If gemstones aren't your thing, but gold is, you can pan for the stuff at Gold Prospecting Adventure, which is located about three hours east of San Francisco.

The center has been open for more than 40 years, and staff will provide you with tools and instruct you on how to pan gold. There are also presentations on the history of the California gold rush.

Emerald Hollow Mine, Hiddenite, North Carolina

Emerald. Source: photo-world/iStock

An hour's drive from Winston-Salem, NC is the 70-acre Emerald Hollow Mine which is the only emerald mine in the U.S. that is open to the public. It is also the only spot in the U.S. where the gemstone Hiddenite can be found. Discovered by geologist William Hidden in 1879, the stone has a lime-green color.

Besides emeralds, the mine also yields sapphires, tourmaline, garnet, topaz, and aquamarine. There is an onsite shop that is available for cutting and polishing your finds, and both military and senior discounts are offered.

Fossil Butte National Monument, Kemmerer, Wyoming

Fossil Butte National Monument
Fossil Butte National Monument. Source: National Park Service

No rock collection is complete without a couple of fossils, and one of the best places to find them is in Wyoming's southwestern desert. The Fossil Butte National Monument has a large number of fossils and activities related to fossil hunting, but remember, as this is a national monument, you cannot dig for fossils here, or remove any that you find. The park is open year-round, but its hours vary with the seasons. 

Entrance to the park is free, and pets are welcome so long as they are on a leash. Be sure to wear hiking shoes and sunscreen as you walk through the park or go on ranger-led programs. 

Juniper Ridge Opal Mine, Lakeview, Oregon

Fire opal
Fire Opal. Source: V&G Studio/iStock

Located in Southeastern Oregon, the Juniper Ridge Opal Mine is home to fire opals. Like a fiery sunset, these stones exude hues of gold, red, and orange, and pieces as large as baseballs are not hard to find.

While Juniper Ridge occasionally allows "fee dig" mining, in which the public can come in and dig for opals, they do not always offer this possibility, so you will need to contact the mine owners before heading out there.

Morefield Mine, Amelia, Virginia

Amazonite. Source: benedek/iStock

During World War II, the Morefield Mine was used for strategic minerals such as mica, beryl, and tantalum. Today, the mine is famous for its Amazonite, a greenish gem named for the river of the same name.

The mine is 300 feet (91 m) underground and stretches for over 2,000 feet (610 m) in length. While you can't use hammers or pickaxes, you can bring home with you anything you can fit into a five-gallon bucket. As of the writing, the mine is temporarily closed, and they tend to be open only on select days, so make sure you check in advance.

Herkimer Diamond Mines, Herkimer, New York

Herkimer "diamonds". Source: TomekD76/iStock

The Herkimer "diamond" isn't actually a diamond, it's a quartz crystal that naturally occurs with 18 facets, which makes it sparkle like a diamond. The Herkimer diamond has a hardness of 7.5 on the Moh's scale, while real diamonds come in at a 10.

Herkimer Diamond Mines is at ground level, the site also includes cabins, camping facilities, fishing, and water sports.

The Rarest Gemstone You've Never Heard Of

Utah Tiffany Stone
Utah Tiffany Stone. Source: SpiritRock Shop

Found in only one place on earth, Utah Tiffany Stone, also known as ice cream opalite or purple opal, is primarily comprised of purple fluorite, but it can also include bertrandite, chalcedony, and opal.

The only place the gem is found in is the Brush-Wellman Mine near Delta, Utah. Bertrandite is a source of beryllium, and it is while mining beryllium that Utah Tiffany Stone is found. Beryllium is a silvery-white metal having atomic number 4 that is used in alloys along with copper or nickel. It is primarily used for aerospace, medical, and military applications.

Utah Tiffany Stone ranks 6 to 7 on the Mohs scale, so it is moderately resistant to scratching and abrasion. Utah Tiffany Stone is partially translucent, but it is primarily opaque and therefore usually shaped into cabochons or sometimes, beads. The stone is popular with lapidarists, and when polished, it becomes lustrous.

Bit by the bug

If you are bitten by the rockhounding bug, the Tucson Gem & Mineral Show occurs every February in Tucson, Arizona. It is the largest gem and mineral show in the world, and it brings together dealers, amateurs, and experts.

The Hope Diamond
The Hope Diamond. Source: David Bjorgen/Wikimedia Commons

If you want to see some of the most eye-popping gems and minerals in the world, the Smithsonian Institution's National Gem and Mineral Collection in Washington D.C. is the place to go. It's home to the world-famous Hope Diamond.

No matter where you search or what specimens you find, rockhounding is a great way to get exercise and fresh air, make new friends, and create memories that you and your family will treasure forever.

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