Treasures on the Yellowstone River
by Kate Bertin
When most people say “Yellowstone,” the image that springs to mind is the national park – Old Faithful, Norris Geyser Basin, lines of cars holding wide-eyed tourists gawking at grazing bison. But there’s another Yellowstone that is full of treasures waiting to be discovered – Montana’s Yellowstone River.
The Yellowstone runs northeast from Yellowstone National Park for nearly 700 miles, until it empties into the Missouri River just over the North Dakota Border. The river is a bucket list destination for many rock collectors, as thousands of years of volcanic eruptions created a wide variety of beautiful stones that have spread all up and down the river drainage.
Most famous, of course, is the Montana Moss Agate, a dendritic agate found largely between Billings and Sidney. Although these translucent gemstones can be found on the river west of Billings, they become more and more scarce as one travels west. Billings itself is a population center in Montana, so the river beaches nearby are picked over quite quickly. The glowing silica rock with tree-like inclusions becomes more plentiful as one travels east along the river. Spots that are hardest to access are naturally the most productive.
But rockhounding on the Yellowstone River doesn’t need to be limited to agates. Petrified and agatized wood can be found in abundance all up and down the river. Multiple volcanic flows created at least 27 different petrified forests stacked on top of each other at the edge of Yellowstone National Park; much of the petrified wood has been carried away down the river. Chunks as large as 30-40 pounds or larger have been discovered at some beaches. The wood is largely agatized, meaning that the wood cells were replaced with silica. This makes thin slabs of the stuff slightly translucent, and it polishes to a beautiful shine. Beyond that, just the idea of picking up a rock that used to be a tree makes it worth keeping!
The third leg of “The Yellowstone Trifecta” is jasper. Jasper, a hard, colorful rock with a conchoidal fracture, is also plentiful on the river. It comes in many hues – red, orange, yellow, green, purple, or swirls of several colors combined. Jasper is not difficult to find, but choosing pieces that will create unique and beautiful pieces of lapidary beauty takes a little time and discretion.
Beyond the “big three,” there are many other beautiful rocks on the beaches of the Yellowstone. Granite, gneiss, porphyry, porcellanite, sandstone, mudstone and dozens of other types and combinations of rocks make up a rainbow of colors. Come visit Montana’s Yellowstone River and discover for yourself why it has “So Many Beautiful Rocks!”
Kate Bertin of YouTube’s KatyDid ROCKS! makes her home in Eastern Montana, and her second home on the beaches the Yellowstone River. She recently published a book about rockhounding the fishing accesses and bridges of the Yellowstone titled “So Many Beautiful Rocks!,” available on her Etsy store.