This is Throwback Thursday #216. In these, we look back into the past at ESCONI specifically and Earth Science in general. If you have any contributions, (science, pictures, stories, etc ...), please sent them to [email protected]. Thanks!
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For this week, we have an article written by ESCONI board member Andy Jansen. Andy took a trip to the "Opal Capital of America" in 2019 and wrote this interesting article for the newsletter.
Opal Hunting at the Spencer, Idaho Mini-Mine
Rock hunting opportunities were dancing through my mind when I was requested to go to Idaho Falls, ID for a business meeting the third week of July. Should I go for fossils, minerals, or both? I was scouring websites for options that would be within a couple hours drive from Idaho Falls in the likely event that my meeting would conclude early. One good choice was an opal “mini-mine” in Spencer, ID, which was only 65 miles north of Idaho Falls, and only 55 minutes, since the speed limit is 80 mph for most of the way. Spencer is a small hamlet (population 33) that is called the “Opal Capital of America.” I packed some “hunting” clothes, safety glasses, hat, and gloves, and watched the weather closely (high 80s with humidity in the teens).
A portion of the falls at Idaho Falls, directly across from the Snow Eagle Brewing & Grill.As luck would have it, my meeting ended early and I had almost 8 hours of daylight to play with. Two of my younger colleagues were willing companions. We stopped at the local Wal-Mart near our hotel to buy a simple 2.5 pound rock hammer, a chisel set, safety glasses, and some gloves, and drove straight north on Interstate 15. (They do permit the use of claw or nail hammers, but they require at least a pair of glasses or sunglasses for eye protection – I opted for more safety and purchased the rock hammer for $8.) The drive is nearly flat, straight, and treeless for the whole 61 miles despite the beautiful mountains off to the west and east of the freeway, and almost no traffic (very strange feeling after spending so many years in Chicagoland). We arrived at the Spencer Opal Mine with nearly 3 hours of collecting time, but first had a quick lunch at the Opal Country Café, which is in the same building as the opal store. This is a family run enterprise that has been in business for 51 years and is now on its third generation. They were very friendly and helpful in the basics of opal hunting and jewelry making.
Arrival at the Spencer Opal Mines café and mini-mine.Google Maps view of the Spencer Opal mini-mine and adjacent café and store.
The mini-mine is located behind the store and can be easily seen on Google Maps – the hamlet of Spencer is very small, with only a few other opal stores that seemed to be closed at the time (we were there on a Wednesday afternoon). If you do decide to go here, make sure to call ahead to confirm they are open as they are only open mainly during the summer tourist months. The actual opal mine is 6 miles away, so they bring a load of crushed rock from the mine almost weekly and mix it into the pile. Naturally, after several decades this pile is getting larger (about a 1⁄4 acre now) and higher. The collecting fee is $20 per person and you are allowed to keep the first pound of rock for free – after which, the price is $10 per pound. This is why the hammer and small chisel come in handy. They provide buckets and an outdoor water tap, which is needed to confirm the opal sparkle. They also provide outdoor and indoor bathrooms – ice cream for purchase too!
My very first opal on top of the mini-mine pile.You will find opals! I found my first opal within ten minutes of picking through the pile. It is hard rock and I wished I had a pair of cheap knee pads. My cotton gloves were shredded after a couple hours. The collecting time ends at 5:00 pm, at which time you bring your finds to the store where they help you sort and weigh your keepers. Since there was three of us, the owners tallied our weight together so that we had a target of 3 pounds, which we easily hit (the owner was also generous with the scale – I think we were closer to 4 pounds when we got home). We now had an hour to browse the store and admire the opal specimens and jewelry for sale (they make the jewelry too – sterling silver and gold).
Specimens of polished opals, and animals (bear and bison) made from layered rhyolite-obsidian, available for viewing and purchase at the store.
My opal treasures after cleaning at home, and a piece of layered rhyolite-obsidian for me to make my own animal. Total weight: 2.25 pounds.
What to do with the remaining 3 hours of daylight? The Montana border (which is also the Continental Divide) was only 10 miles north of Spencer. We decided to head 30 miles north to have dinner in Lima, Montana (pronounced like lima beans) where there is also a new rest area with a few placards on local items of interest. Lima is a small town (population 228), but it does have a nice restaurant called Jan’s Café where we decided to eat. Another interesting feature of this café is that it has 8 Tesla electric vehicle charging stations. For those of us interested in fossils (and who isn’t?), there was a dinosaur discovery near Lima in 2006 of an adult Oryctodromeus and two juveniles, which were small herbivores that lived in underground burrows 95 million years ago. This is described on a placard at the Lima rest stop.
This was a very easy adventure from Idaho Falls to Spencer, ID to Lima, Montana. We were never more than a quarter mile from Interstate 15. The one drawback is the limited choices in flights to Idaho Falls – you have a choice between flying through Denver or through Salt Lake City. I flew through Salt Lake City, which provides a spectacular view of the city and the Salt Lake. Of course, you could always drive, in which case you can bring all your rock hunting gear. Next time, I will try finding fossils at a couple locations my Idaho Falls colleague recommended. Stay tuned.