Over the many years since I moved to Colorado Springs and started collecting minerals (as opposed to vertebrate fossils in my professional career) I had the opportunity to purchase micromount minerals (some mounted in a Perky or similar box) from Sauktown Sales. At first my purchases were few and far between, but as I began to run out of personal space and cabinets for larger hand-size specimens, I turned to the world of micros and thumbnails. I soon found out that Jim, the owner of Sauktown, was based in Mill Creek, Indiana, and essentially was a one-man show with an extensive inventory. Soon my monthly purchases increased, and I started to “have conversations” with Jim. I found it interesting that when I placed an order Jim sent the specimens and then an invoice and I paid with a mailed check. That trust is not found in many businesses today. Jim also took “special orders” and one month I simply asked for 20 specimens originally mounted by Art Smith a few decades ago. He sent them with a note stating that “enclosed were 20 of his more interesting mounts”. This last 2023 winter I sent in an order but did not receive confirmation. A couple of months later I sent another email with the same results. Last week I received a note from his daughter Susan that Jim suffered a fall and a broken hip in February, never fully recovered, and passed away in early June at age 87. He was a very friendly guy, and I shall miss our conversations but really miss those micromounts. RIP my friend.
That information spurred me to reach into my magic drawer and pull out a small, unmounted specimen received several years ago but never really examined closely—brochantite from the Blue Crystal Mine in San Juan County, Utah.
The Blue Crystal is located near Moab, Utah, south of the nearby La Sal Mountains in Lisbon Valley. The Valley is home to one of the better-known local uplifts, the Lisbon Valley Anticline, a large salt anticline where the dipping beds are due to movement/solution of salt in the subsurface. Several of these salt structures are found in the greater Paradox Basin, an evaporate basin in Utah and Colorado near the Four Corners. Although the Valley has several tens of producing gas wells, the most active mineral commodity has been the numerous uranium mines (earliest report in 1913) and the area is undergoing uranium resurgence today. Target zones have been, and still are, the Cutler Formation/Group (Permian), the Moss Back Member of the Chinle Formation (Triassic), and the Salt Wash Member of the Morrison Formation (Jurassic) found along the flanks of the anticline.
Copper is also present in varying quantities and qualities in Lisbon Valley and has been periodically mined for decades. Most of the paying copper deposits seem to be in the Dakota Sandstone and Burro Canyon Formation, both Cretaceous in age---therefore younger and above the uranium beds. The major copper ore is chalcocite (Cu2S) deposited by solutions brought up along the Lisbon Valley Fault (found along the crest of the anticline with offset approaching 4000 feet). With time, chalcocite oxidizes to such secondary minerals as azurite [Cu3(CO3)2(OH)2] and malachite [Cu2(CO3)2(OH)2], both copper carbonates, (but note that azurite commonly pseudomorphs to malachite), and tenorite [CuO] and cuprite [Cu2O], both copper oxides.
One of the earliest mining areas in the Lisbon Valley/La Sal District was originally organized in 1892 and generally went under the name of Big Indian Copper Mine with later mines and claims termed Blue Jay Claim, Blue Grotto Prospect, Nevada Claim, Blue Crystal Mine, and the Texas Claim. A copper processing mill was constructed in 1918 and mining continued sporadically for several decades. The ore body is comprised of oxidized copper minerals (see above) emplaced in the Cretaceous Dakota Sandstone along the downthrown side of the Lisbon Valley Fault; mining has been via open pit and tunnels. In the late 1970’s prospectors started to notice beautiful azurite crystals and specimen collecting went into operation. For example, in 1988 a cut on the Nevada Claim produced one hundred thousand specimens of azurite rosettes (for collectors) and 6000 pounds of broken nodules for paint pigment. Today the claims are generally referred to as the Blue Crystal Mines and the miner/operator is present at many mineral shows in the West, including Tucson (usually in the 22nd Street complex).
The most unique of the specimens collected at the Blue Crystal Mine, then and now, are the “blueberries”, small (up to a centimeter or two) concretions, often hollow, of micro azurite crystals; some contain tiny, rounded quartz grains mixed with azurite. I have not been able to locate information about their formation; however, it appears that tens of thousands of these “blueberries” have been collected over the decades. Rockhounds in Utah tell me that the mine is the single world source for these unique specimens; however, I have seen similar/almost identical specimens from the El Chino Mine in New Mexico, and perhaps others.
The “azure colored” rosettes and crystal clusters “commonly occur as 3-8 cm masses of subparallel crystals and as individual crystals to 2.5 cm in length” (Hampson, 1993). The blueberries are much lighter in color, perhaps sky blue.
Below: Three photomicrographs detailing submillimeter size malachite pseudomorphs.
I originally ordered the specimen due to its collecting location (Utah), and the fact that the mineral brochantite (one of my favorites) was listed. However, not every purchase in the mineral world turns out as noted. I have never been able to identify brochantite on this thumbnail specimen! MinDat has brochantite listed as present (without photos); however, Hampson (1992) stated “A number of old malachite specimens were incorrectly labeled brochantite; no brochantite has been reported from this location (Dick Dayvault, pers. com.).” I agree with Hampson (at least in my specimen) that the tiny green radiating sprays, and the masses of tiny acicular green crystals” are malachite.
However, all was not lost since one small side of the thumbnail has numerous light green octahedrons displayed. It turns out these crystals are cuprite that have been altered to malachite—an interesting pseudomorph.
REFERENCES CITED
Hampson, A. G., 1993, Minerals of the Big Indian Copper Mine San Juan County, Utah: Rocks and Minerals, v. 68, No. 6.
As the Rolling Stones noted in 1969 on their Let It Bleed album:
No, you can't always get what you want
You can't always get what you want
You can't always get what you want
But if you try sometime you find
You get what you need
Wow, that little ditty sometimes just sticks in my mind and takes me back a few years!! The trivia: that was a B side song, and the A side was Honky Tonk Women.