Discovery of World Class Heulandite and Mordenite near Challis, Idaho
See the article in Rocks & Minerals, March-April, 2001, Vol. 76, No. 2, p. 113.
Sometimes, with a lot of work, we find what we are looking for. I make a few mineral collecting trips each year, and much of this time is spent exploring for minerals, not actually breaking rock at a known locality. Exploration takes a lot of time and has few successes, mostly it is fun, one can't ignore the desire to be outdoors hiking in the mountains or climbing over mine dumps looking for interesting minerals. I like to explore and often spend several years trying to find a locality that is vaguely described in the literature. Such is the case with a report of mordenite and associated zeolites near Challis Idaho. An old National Museum article (Proceedings, 1924) described some specimens of mordenite, heulandite and other minerals from "the low hills south of Challis, Idaho." Believe me, that is a vague locality description! If one considers that south of Challis there are only a few low hills before one gets into some rather rugged country that quickly rises 4,000 feet above town, it is difficult to figure out where the locality would be.
While searching in the area for agates for a guide book, I discovered stilbite on Lime Creek, about 8 miles SE of Challis. It was no surprise after finding that location that I learned it was known by others. Although they may not have known of the specific canyon I discovered because it had stilbite crystals exposed in open cavities, generally not a common site in a known locality, but there were other occurrences along the creek which were known.
However, this still didn't get me to the mordenite and other zeolites of that old report. On other excursions, I found more agate and jasper, but no zeolites. One exploration hike took me to within about 2 miles of the location of the recent discovery. Other than a little low grade agate, all that produced were signs of wild horses and a few fast moving antelope.
A few other "old time" collectors reported occurrences of small zeolites in the area, but these were either difficult to access due to the private land, or were small crystals of common zeolites in roadcuts and obviously not three foot diameter geodes lined with mordenite.
Finally in the fall of 1999, I received a lucky break. A friend who was raised in Challis reported that he was interested in looking for zeolites in an area that he had seen some chunks of massive zeolites when on a field trip in grade school, many decades ago. His interest is mineralogic/scientific, not specimens, and he is unable to hike great distances. I'm proud to do the leg work for him, he gets mineralogic specimens, and I learn a lot more from his knowledge and analyses of the specimens. Anyway, to make a really long story not too long and boring, we met in town, did some looking elsewhere for an afternoon, camped out on the Salmon River (can't beat mineral collecting for getting out and enjoying the wilds of the Pacific Northwest!), and the next morning drove over to the ranch he wanted to get access through. We asked, they allowed us to pass through and we drove up into a canyon area. My friend proceeded to explore near the truck and I proceeded to hike up into the hills and ridges.
As usual, I saw a little of this and little of that and nothing even closely resembling zeolites or anything mineralogically worth picking up. Looking across the canyons, I noticed what appeared to be an old overgrown pit on a far ridge. Hmm, must be an old mineral exploration pit of some kind--my thick skull didn't even suggest that this might be the small pit mentioned in the old National Museum article. Anyway, I proceeded to hike around a few more hills and towards the end of that day, stumbled onto a few pieces of coarse heulandite. Follow the float train! Sure enough, here's the zone and... Well, the story is: a new discovery of heulandite- and mordenite-bearing geodes with mordenite lined geodes to 3 feet across (so far, maybe there are some big ones in there!) and heulandite and mordenite lined geodes to up nearly 1 1/2 feet across with heulandite crystals up to more than 2 inches! And the heulandite comes in colorless, white, golden cream color, various pinks and even salmon colored orangish pink and a reddish orangish pink!