Montana is an extraordinary state for rockhounding. The state – known as the ‘Treasure State’ – is well known for its enormous copper (the 'richest hill on earth') and coal deposits as well as an 1800s gold rush. In addition, the state is famous for its sapphires and its agates. Today, however, the state is world-renown for its dinosaur fossil sites. It also is home to some very unusual ringing rocks. I enjoy rockhounding in Montana ... and visiting my grandparents … even though I was nearly hit by lightning. Really!
State Rocks, Gemstones, Minerals, Fossils, & Dinosaurs
Rockhounding Tip: Knowing state rocks, gemstones, minerals, fossils, and dinosaurs often can be very useful information for rockhounders. Ordinarily, states with significant mineral deposits, valuable gemstones, fossils, or unusual or significant rock occurrences will designate an official state mineral, rock/stone, gemstone, fossil, or dinosaur to promote interest in the state’s natural resources, history, tourism, etc. Accordingly, such state symbols often are a valuable clue as to potential worthwhile rockhounding opportunities.
State Gemstones: Montana Agate & Sapphire (1969)
Montana designated both the Montana agate and sapphire as its two official state gemstones in 1969. Montana is well known for its ‘Montana agates’ (or ‘moss agates’) that can be found in the gravel beds of the Yellowstone River in southeastern Montana. ‘Moss’ refers to the dendritic patterns that may occur in the agates as moss-shaped inclusions, resulting from the presence of manganese or iron oxides.
In addition, Montana also is well known for its sapphires. Sapphire is a variety of corundum. Red corundum is called ruby while all other colors are called sapphire. Sapphire is found as an accessory mineral in metamorphic rocks. In 1865, the first U.S. sapphires were found in the gravels of the Missouri River in Lewis and Clark County, Montana. This was followed by subsequent discoveries on Dry Cottonwood Creek in Deer Lodge County in 1889, on Rock Creek in Granite County in 1892, and in Yogo Gulch in Judith Basin County in 1895. Small amounts of sapphire also are recovered from Quartz Gulch in Granite County, Pole Creek in Madison County, the Missouri River in Chouteau County, and Brown's Gulch in Silver Bow County. In addition, corundum crystals, from which star sapphires have been cut, are found in Beaverhead and Madison Counties.
State Fossil: Maiasaura Peeblesorum (1985)
Montana designated the duck-billed dinosaur Maiasaura peeblesorum as its official state fossil in 1985. Maiasaura peeblesorum lived on the coastal plains and lowlands along the Cretaceous Interior Seaway about 80 – 70 million years ago. Fossil localities have yielded multiple nests and the remains of over 10,000 individuals, suggesting that these hadrosaurs lived and cared for their young in herds. Maiasaura are in the "hadrosaurs" family. All hadrosaurs were medium-sized, bipedal, herbivorous dinosaurs of the Upper Cretaceous Period with long flat snouts and a crested skull. They also had three toes on the hind feet and four toes on the front. An adult Maiasaura was nearly thirty feet long, weighed about three tons, and had a tiny knob between its eyes. The dinosaur walked on its hind legs, with its tail held out straight for balance. When newly hatched, the duck-billed dinosaur was less than fourteen inches long and weighed about one and a half pounds. Adults grew to over thirty feet in length and weighed three tons. One of the most significant paleontological discoveries of the latter 20th century came in 1978, when fossils of a nesting colony of duck-billed dinosaurs were found west of Choteau, Montana (now known as ‘Egg Mountain’). The findings at Egg Mountain provided valuable evidence that Maiasaura nested in extensive colonies and had nests six feet in diameter with as many as twenty eggs. The nest was seven feet wide and two and one half feet deep, and shaped like a bowl. It's believed the young may have remained in the nest for up to two months. This demonstrated for the first time parental care of dinosaur young. Paleontologist Jack Horner and research partner Bob Makela determined that the species, which they named Maiasaura (“good mother lizard”), raised its young in colonies, as many birds do, rather than abandon the nest after laying eggs, like reptiles. The second part of its scientific name, peeblesorum, honors the Peebles, a Montana ranch family from the Choteau area where the discoveries were made.
State-specific rockhounding books (including the books listed here as well as other books), regional rockhounding site guides, and other helpful rockhounding resources are identified - by category - in the Books & Gear section of Gator Girl Rocks with a link to the Gator Girl Rocks Amazon Store where you may easily browse selected resources and securely place an order. Your order will benefit Charity Rocks!
Montana Bureau of
Mines & Geology
Functions, in part, as the state’s geological survey.
US. Bureau of Land
Management – Montana/Dakotas
Office publishes - Rock Hounding On Public Land In Western Montana (Rev. 8/06) an informative six-page guide regarding rockhounding on federal lands managed by the BLM.
U.S. Forest Service
The Forest Service manages enormous amounts of federal public lands in Montana. Subject to federal restrictions (and district restrictions), portions of some of the National Forests in Montana are open to recreational rockhounding. The USFS publishes a useful overview.
Includes information on several Montana museums with dinosaur and fossil collections.
- David D. Alt & Donald W. Hyndman, Roadside Geology of Montana (1986)
- Montana Hodges & Robert Feldman, Rockhounding Montana (2d ed. 2006).
- Robert Feldman, The Rockhound’s Guide to Montana (1985).
- Lanny R. Ream, The Gem, Mineral, & Fossil Collector’s Guide to Montana (1992).
- Jack Horner, Dinosaurs Under the Big Sky (2001).
- H.C. Dake, Northwest Gem Trails (2d ed., 1956 – originally published in 1950).
- Allan W. Eckert, Earth Treasures Vol. 3 - Northwestern Quadrant (1986; reprint in 2000)
- James Martin Monaco & Jeannette Hathway Monaco, Fee Mining & Rockhounding Adventures in the West (2d ed. 2007)
- Kathy J. Rygle and Stephen F. Pedersen, Northwest Treasure Hunter's Gem & Mineral Guide (4th ed. 2008)
Museums of Interest to Rockhounders
Museum of the
Montana State University – Bozeman, Montana
Showcases one of the largest and most important dinosaur collections in the world. The museum is known for its paleontological collection. Based on the research of paleontologist and advisor to the Jurassic Park films, Dr. Jack Horner, the Museum features T. Rex, Triceratops, Torosaurus, and more. The museum houses the most T.rex specimens anywhere in the world - currently 13.
Montana Tech - Montana Bureau of Mines & Geology - Butte, Montana
The Mineral Museum overlooks the 100-year old Butte Mining District. Includes classic mineral specimens from Butte's underground mines, which include over 3,000 miles of mine workings that reach over a mile deep. The museum's collection has over 15,000 specimens from worldwide localities, and 1,300 spectacular minerals from the Butte mines, including a 400-pound smoky quartz crystal.
University of Montana Paleontology Center
University of Montana – Missoula, Montana
The UMPC collection contains an estimated 100,000 specimens with over 1,500 representing type (published) specimens. Displays featuring some of the UMPC holdings are located on the first and third floors of the Charles H. Clapp Building.
World Museum of Mining
The museum’s mineral room exhibits local rock and mineral specimens.
Two Medicine Dinosaur Center
The Two Medicine Dinosaur Center houses a wide variety of dinosaur species, invertebrates, plant fossils, archeological materials, and cultural items. Also on display are some of Montana's rarest fossil discoveries. One such is a display of the first infant Maiasaura bones from the famous Egg Mountain area.
Phillips County Museum
Seventy million years ago, that area that would become Phillips County, Montana was a shoreline along a massive inland sea. As a result, this area of Montana is includes numerous fossil deposits. The museum exhibits several fossils excavated from the Judith River Formation, including a complete 33-foot-long Brachylophosaurus skeleton as well as an Albertosaurus and many locally discovered fossils.
Rudyard Historical Society Dinosaur Museum
This small museum exhibits dinosaur fossils including Maiasaura, Troodon, Tarasaurus, and Rudyard’s own Gryposaurus. The museum collaborates with the Museum of the Rockies to rotate exhibits.
Central Montana Museum
The museum exhibits rocks, minerals, gems, and fossils. The museum also includes a full-scale replica of a Torosaurus dinosaur skull that was found in the Valentine area (about 65 miles east-northeast of Lewistown).
Earth Science Museum
Northeast of Fort Benton in Loma, Montana
The museum exhibits local rocks, minerals, gems, and fossils.
Places to Visit - Interesting Sites To See
Glacier National Park includes glaciers, glacially carved mountains, and Precambrian era rock formations. In addition, the Park includes some of the oldest fossils in the world (stromatolites occur in the 1.5 billion year old limestone and dolomite in the Altyn Formation).
Southern Montana (as well as Idaho & Wyoming)
A small portion of America’s First National Park – Yellowstone National Park – extends into Montana. Yellowstone, of course, is amazing. Visitors can see fossilized trees, geysers, hot springs, bubbling mudpots, steaming fumaroles, travertine formations, and obsidian cliffs – all within an ancient, but still active, giant volcanic caldera. Yellowstone National Park is home to one half of the world’s geothermal features. Its more than 300 geysers make up two thirds of all those found on earth.
About 25 miles East of Billings, Montana - The Pillar overlooks the Yellowstone River
Pompey's Pillar is one of the most famous sandstone buttes in America. It bears the only remaining physical evidence of the historic and courageous Lewis and Clark Expedition, which appears on the trail today as it did over 200 years ago. On the face of the 150-foot butte, Captain William Clark carved his name on July 25, 1806, during his return to the United States through the beautiful Yellowstone Valley. Captain Clark named the pillar "Pompey's Tower" in honor of Sacagawea's son Jean Baptiste Charbonneau, whom he had nicknamed "Pomp." Nicholas Biddle, first editor of Lewis and Clark's journals, changed the name to "Pompey's Pillar."
Berkeley Pit Copper Mine - Richest Hole on Earth
Enormous former open-pit copper mine approximately one mile long and a half-mile wide. The pit is over 1,700 feet deep.
Montana Dinosaur Trail
Statewide information about Montana sites and museums regarding local dinosaur sites.
Ringing Rocks Pluton
Between Butte and Whitehall, Montana
Montana’s unusual ‘Ringing Rocks’ formation is located in the Deerlodge National Forest (managed by the BLM), approximately 20 miles east of Butte, Montana in the Rocky Mountains [Exit 241 (Pipestone) from Interstate 90]. The Ringing Rocks ring like a bell when lightly hit with a hammer. The Ringing Rocks are a very small part (about 160 acres) of a mountainous region called the Boulder Batholith, which encompasses a large portion of southwestern Montana. Batholiths originate when magma cools slowly beneath the surface to form granite. Following uplifting and erosion, the granite is exposed. Pennsylvania also has ringing rocks.
Lewis & Clark
Caverns State Park
Between Bozeman and Butte, Montana
Montana's first and best-known state park showcases one of the most highly decorated limestone caverns in the Northwest. Naturally air conditioned, these spectacular caves are lined with stalactites, stalagmites, columns, and helictites.
Tom Miner Basin Petrified Forest
Gallatin National Forest – North of Yellowstone National Park
The Tom Miner Basin, which is federal public lands managed by the United States Forest Service, contains a petrified forest. The Eocene era petrified forest is between 55 and 35 million years old. The site is unique because many of the fossilized trees are vertical. There is an interpretive trail. The specimens are interesting to see.
Earthquake Lake Visitors Center – West of Yellowstone National Park
The Madison River Canyon Earthquake Area is the site of a significant and devastating earthquake in 1959 (28 people were killed). The earthquake measured 7.5 on the Richter scale (the largest recorded earthquake in the United States at the time) and sent eighty million tons of mountain into the Madison River. The US Forest Service’s Earthquake Lake Visitors Center is located approximately 25 miles from West Yellowstone, Montana.
Granite Ghost Town
Granite County, Montana
Several historic ghost towns are located in Granite County Montana. The Granite County Museum located in Philipsburg, Montana is home to the Montana Ghost Town Hall of Fame. Nearby, the Philipsburg area is home to several ghost towns including Granite, which was nicknamed ‘Montana’s Silver Queen.’ The ghost town of granite is located on Granite Mountain four miles east of Philipsburg.
Rockhounding Sites for Children & Families
Amethyst, Smoky Quartz
Crystal Park - Beaverhead-Deerlodge National Forest
The Crystal Park site is under claim to the Butte Mineral and Gem Club and is jointly maintained and supervised by the club and the Beaverhead National Forrest. The site is located 7,700 feet above sea level in the Pioneer Mountains of the upper Big Hole Valley southwest of Butte, Montana in the Beaverhead-Deerlodge National Forest.
This site has been a favorite with recreational rockhounds for decades because of the exceptionally well-formed quartz and amethyst scepter crystals. Lucky rockhounds also might find a "Japan Law Twin,'' a pair of crystals joined at an unvarying angle of 84 degrees, 39 minutes. Another prize is a "scepter,'' a larger crystal on the end of a smaller one. The Butte Mineral and Gem Club began filing mineral rights claims at the area in the late 1950s. In 1976, the group entered into a cooperative agreement with the Forest Service for the management and development of Crystal Park for public recreation. The club contributed funds for a boundary fence and portable toilets. Crystal Park is about 65 miles SW of Butte. From Butte, take Interstate 15 south about 25 miles to the exit to Divide. Take MT 43 about 11 miles to the town of Wise River. At Wise River, take the Pioneer Mountains Scenic Byway Road approximately 25 miles to Crystal Park.
Gallatin National Forest – North of Yellowstone National Park
The Tom Miner Basin, which is federal public lands managed by the United States Forest Service, contains a petrified forest. The specimens are interesting to see. Subject to federal restrictions and obtaining a permit (in advance), individuals are allowed to collect a single twenty cubic inch specimen (about fist sized). Sadly, of course, people abuse the site.
Gem Mountain Sapphire Mine - Near Phillipsburg, Montana
Commercial (fee access) business. Visitors can screen gravels from the famed Rock Creek Sapphire site. These are pictures from 2007 when we took my grandparents to look for sapphires to celebrate their 45th wedding anniversary (the sapphire anniversary).
Spokane Bar Sapphire Mine & Gold Fever Rock Shop
Commercial (fee access) business. Visitors can screen gravels from Missouri River gravel terraces. The geologic structure called Spokane Gravel Bar is a deposit consisting of unsolidified sediments, deposited by an ancient river. The site is located near Hauser Lake along the Missouri River (near Helena, Montana). Discovered in the early 20th century by geologists mapping the Missouri River area, the site was named after the Spokane Hills that are composed of Spokane shale. The present river level is more than 50m below the ancient river deposits. Four major gravel terraces are visible on both sides of the river.
Yellowstone River, Montana
‘Montana agate’ or ‘Montana moss agate’ specimens may be found along the Yellowstone River’s extensive route through Montana. Although many collectors favor sites near the North Dakota border, I’ve found agates just outside Yellowstone National Park at the opposite end of the river.
Limonite Cubes -
Cooper Lake – NE of Helena, Montana
This site is located within the Helena National Forest. Limonite has replaced the pyrite cubes forming fascinating psuedomorphs. Most are less than one-half inch, but occasionally as large as two inches.
Limonite Cubes - Pyrite Psuedomorphs
Limonite has replaced the pyrite cubes forming fascinating psuedomorphs. The matrix rock is the billion-year-old Belt Formation. I visited the site in 2009. A thunderstorm rolled in and my grandpa, dad, and I had to wait it out inside a small cave, as the lightning was right on top of us. My hair stood on end … but, I found some terrific specimens.
Montana City, Montana
Exit 187 off of Interstate 15 - Road cut on NW side of interchange
Calcite crystals (and rattlesnakes) can be found in the Rattler and Spring Gulch areas approximately 4 to 5 miles northwest of Drummond. In 2008, while visiting the area, I found both.
Smoky Quartz Crystals – ‘Montana
Judith Peak – North of Lewistown, Montana
Doubly terminated smoky quartz crystals can be found near the top of Judith Peak, north of Lewistown, Montana on federal public lands managed by the BLM in Fergus County. The small crystals – sometimes called ‘Montana Diamonds’ – weather from porphyritic rock.