The editor would like to apologize for the lack of pun-y title. There’s got to be clever plays on the word “agate” but we just couldn’t think of one.
Growing up, our house always had a collection of “interesting rocks.” Whenever we were walking around, if we saw an interesting rock, we would say “huh, that’s an interesting rock,” pick it up, and deposit it on the windowsill of our mudroom when we got home. We never really did anything with them, just had them. Most Montana homes I’ve visited have similar rock-strewn mudroom windowsills. It strikes me that if you sifted through all these collections of interesting rocks you might be able to make a very (very, very, very) small fortune. That is because many of these rocks are actually Montana moss agates,
Agates are fascinating rocks. Imagine an ordinary river rock. Now imagine that instead of dull and rough, the rock is cloudily translucent, full of hues of yellow, blue and brown, and glassy-smooth. Agates form when silicon-rich water gets trapped in cavities within cooling magma. These cavities are often just air-pockets but are sometimes casts of tree limbs or other organic matter. As any connoisseur of Montana Department of Transportation Geologic Road Signs is aware, about 60 million years ago, Montana was a hotbed of volcanic activity and most of our agates date from that period. For specific science-y reasons that I’m not going to get into (but which I totally understand) agates have different layers of color throughout them. Many agates have distinct bands of color, but the colors in Montana moss agates are more amorphous and often look like drifting clouds, landscape horizons, or—hey!—moss. In Montana they are most common along the Yellowstone River, but they can also be found in other areas of former volcanic activity like the Boulder Batholith in SouthWest Montana.
In 1969 Montana state representatives named both agates and sapphires Montana’s official state gemstones. I’ve noticed that agates tend to get over-shadowed by Montana’s globe-trotting Yogo Sapphires—“the finest precious gemstones ever found in the United States”—but agates have their own unique charm—especially since an amature rockhound is more likely to find an agate. Moss agates, with their mossy yellows and browns, are the state gemstone, but you can also find other sorts, from precisely banded samples to vivid blue varieties. Agate hunting is a superb way excuse to explore off the beaten path, and, with any luck, you’ll walk away with a unique Montana souvenir.
If the idea of rockhounding tickles your fancy, be sure to check out Falcon’s Rockhounding in Montana: A Guide to 100 of Montana’s Best Rockhounding Sites, which is a great guide, and has excellent information about Montana’s rock hunting regulations. Even if you don’t go traipsing through the wild, stores across Montana have all sorts of found-in-Montana agate souvenirs.