BLACK HILLS COSMOS AND HUREAULITE

Outcrops of the Proterozoic Harney Peak Granite (~1.7 Ga) exposed along the Needles Highway northeast of Custer.  Note the vertical joints and their relationship to the “needles.”

One of my early trips to the Black Hills of South Dakota was during a summer camping trip with a couple of college friends.  We were getting prepared for fall classes and “needed” a break from our summer of manual labor.  As usual, my father was not overly pleased with my absence from work; however, we were 20 years of age with borrowed IDs (well maybe that was just a dream since such action was illegal) and wanted to head west and see bears and mountain lions and climb mountains.  We were all small town kids and escaping a town of less than 400 persons and several dogs certainly was a major priority.  So, off we went ready to hunt for Custer’s gold, and meet wild women (well maybe not wild but just any females our age).  After a couple of days we sort of changed our failed priorities to better reflect realities, especially of the “boy meets girl” project!

Anyway, upon reaching South Dakota we spent some time in Badlands National Park and I became fascinated with the “wildness” of the area and the numerous vertebrate fossils.  Little did I know that in a few years I would be tromping around the badlands trying to complete a graduate thesis. Upon driving over to the Hills we took in the requisite tourist sites such as Mt. Rushmore, a fairly sleepy national monument in those days, Reptile Gardens (still there) and a place called the Cosmos Mystery Area.  The Cosmos “was discovered in 1952 by 2 college boys looking for a place to build a summer cabin.  When they entered this area they experienced a slight unbalance which increased considerably on entering the old house. The boys were interested and camped on the place while they investigated the odd phenomena.  They decided that here was something of interest to the general public, so they began to fix the cabin to make it safe and then developed the demonstrations that you will experience on our guided tour” (www.cosmosmysteryarea.com). In other words, there was money to be made from the gullible tourists, including three backwards kids from central Kansas.  We had a ball at Cosmos and came back to camp, actually with a stop at a German Beer Garden, determined to sketch out the whys and wheres of the paranormal experience---after all we were smart college kids with a science background, and cold Coors beer will fuel anyone’s imagination.  If you are really interested in the experience of Mystery Spots (and they are multiple localities in the U.S.), check out the web site at www.sandlotscience.com. 

Now, why in the world did my mind bring up that long-ago experience at Cosmos of the Black Hills?  My answer is that I was thinking about preparing a small Blog offering on the mineral hureaulite, a hydrated manganese phosphate (Mn,Fe)₅(PO₄)₂.  OK, so what. Well, hureaulite is “reputed to be a kundalini stone... as the golden light it emits can move up from the base and sacral chakras through the entire body, and stimulate the awakening of the kundalini” (http://www.healing-crystals-for-you.com). 

So, with my kundalini activated I was brought to several “heightened states of mental functioning such as genius, creativity, inspiration, revelation, mystical experience, and paranormal faculties of mind”(www.kundalinistones.blogspot.com).  I am guessing that my kundalini revved my mystical experience at Cosmos of the Black Hills those many years ago.  Now, with my creativity in high gear, I need to finish this posting! 

As readers know, I have a great love for the Black Hills and several Blogs are dedicated to the geology and rocks and minerals of this Laramide (late Cretaceous-early Tertiary) mountain range.  If any readers plan on exploring the Hills I would suggest a really wonderful book entitled Guidebook to the Geology of the Black Hills, South Dakota (Lufkin and others, 2009).  Although somewhat technical, the photos and the maps should excite any rockhound, and geologists will sleep with it under their pillow in order to transfer information to the brain.

The book covers many of the old mines in detail, but one of particular interest is the Tip Top mine near Custer.  The pegmatite exposed in the workings has produced at least 92 minerals, 12 of which call the mine their type locality and seven of which are endemic to the TipTop.  Mining for tin at the Tip Top commenced in the 1880s but was a fizzle.  In the first half of the 20^th Century the Tip Top was mined for various varieties of feldspar and in the early 1980s beryl was produced (Lufkin and others, 2009).  Today the mine is leased by Tom Loomis (www.dakotamatrix.com), one of the authors of the geology book noted above. 

The amazing “thing” about the Tip Top, besides the 92 known minerals, is the large number of microscopic minerals coming from the “?hydrothermally altered beryllium and phosphatic rocks” (Lufkin and others, 2009)—it is a micromounter’s paradise.

I have a tenacity to pick up minerals from the Hills if I see such offered by dealers (at a reasonable price).  A couple of years ago, when perusing the smaller venues at Tucson, I nabbed a small specimen of the above mentioned hureaulite [(Mn,Fe)₅(PO₄)₂(HPO₄)₂-4H₂0] collected at the Tip Top.  At least I believe it is hureaulite as well as some other unidentified minerals!

Red to pink hureaulite from Tip Top Mine.  Length of largest mass ~9 mm.

Although hureaulite can appear in a number of colors—red, many shades of white, brown, yellow—pink to red seems to be the dominant color (i presume manganese is the chromophore).  Although some specimens display nice crystals---see MinDat---others are composed of compact masses of indistinguishable crystals.  They range from transparent to translucent and are quite brittle (know from experience).  The hardness is ~5 (Mohs) and the mineral displays a less than vitreous to greasy luster.

MinDat notes that hureaulite is associated with triphylite and is probably a secondary weathering product of the mineral.  Triphylite is a fairly common lithium iron phosphate in solid solution with lithiophylite, a lithium manganese phosphate.  Both, along with the common apatite, are primary phosphates crystallizing from late stage magmatic solutions.  Hureaulite is a secondary mineral forming in low temperatures from the oxidation (weathering in the presence of water) of the primary minerals.  It seems as if water removes the lithium from the primary minerals and leaves behind the iron and manganese.

So, a long ago college trip to the Black Hills was the initial stage of my fascination with the western part of South Dakota.  I did not direct my life.  I didn’t design it.  I never made decisions.  Things always came up and made them for me.  That’s what life is. (B.F. Skinner)

REFERENCES CITED

Lufkin, J.L., J.A. Redden, A. Lisenbee, and T. Loomis, 2009, Guidebook to the Geology of the Black Hills, South Dakota: Golden Publisher, Golden, CO.

GOLD HILL HIDALGOITE (ARSENATE)

The Gold Hill Mine complex (AKA Western Utah Mine and the Clifton District) is located at the northern end of the Deep Creep Mountains in western-most Utah.  I first became acquainted with the mountains and the mining area during my stint at the University of Utah in the late 1960s. Later in life I had a vertebrate fossil collecting project near the western edge of the Deep Creeks but located in Nevada (Nelson and Madsen, 1987).  I remember the area as being one of the most desolate collecting sites that I worked, and made certain that my student assistants remained in visual site of each other. 

 

Google Earth© image showing location of Deep Creek Mountains (Deeps), Salt Lake City (SLC), with I-80 leading to Wendover (W).

The Deep Creeks are located along the Utah-Nevada state line about 30 miles south of Wendover, Utah/Nevada.  Yes, Wendover, Utah, holds the parking lot for the casinos at Wendover, Nevada.  The towns are about 120 miles west of Salt Lake City along I-80 in the Bonneville Basin (home of Pleistocene Lake Bonneville and the much smaller Great Salt Lake).

The town site of Gold Hill (at the mining complex) is still occupied by a small number of persons, and several dogs, which seem to enjoy the solitude and their freedom.  The mine was opened in the mid-1800s and closed for gold mining in the mid-1920s.  During the period of WWI the mines reopened to produce arsenic and in the 1940s (World War II) Gold Hill was reopened to produce tungsten; however, during the mine’s lifespan silver, lead, copper, lead, zinc were also produced.  The mineralization began at Gold Hill approximately 152 Ma as magma was intruded into the overlying Paleozoic rocks---rich in silver, gold, arsenic, copper, and lead (Robinson, 1993).  A second stage of mineralization commenced in the early to middle Tertiary (perhaps 38 Ma) when magma again intruded into Mississippian to Pennsylvanian sedimentary rocks---rich in silver, lead copper and gold In addition, extrusive volcanic rocks, ~8 Ma, created some low-grade beryllium mineralization (Ege, 2005; Robinson, 1993).  A much more extensive discussion of Gold Hill may be found in the Blog Posting on January 3, 2015: Gold Hill, Utah, Arsenates.

Gold Hill is famous among mineral collectors as MinDat lists 102 valid minerals plus several varieties. It is the Type Locality for Austinite and Juanitaite but the copper and arsenate (contain the AsO₄ radical) minerals are often spectacular. 

This small posting will document another addition to my small Gold Hill collection, the rare lead aluminum arsenate hidalgoite [PbAl₃(AsO₄)(SO₄)(OH)₆].  The specimen, with what I identified as hidalgoite, was picked up from a dealer and was noted as coming from the ?80’ level and is a product of weathering in the oxide zone of metallic sulfide deposits (containing lead).  Hidalgoite is sort of non-descript usually occurring as a druze or spherulitic encrustation; however, at the type locality (Zimapan Mining District, Hidalgo, Mexico) the mineral occurs as dense white masses.  In some localities the mineral is colorless; however, the specimens I have observed from Gold Hill are tan to orange to shades of green.  In addition, the Gold Hill specimens are usually associated with “limonite” and secondary rust coloration may hide the true color.  Under the rust the spherulitic encrustation of my specimen reveals microscopic crystals (appearing translucent) tending to a tan color.  I tried to determine hardness but will settle for MinDat specification: ~4.5 (Mohs). The luster is rather dull/earthy and the streak is white.

Spherulitic encrustation of tan to orange hidalgoite composed of microcrystals; each spherule ranges from .3-.5 mm. I am uncertain about the composition of the green mineral.

I also found a story in a 2014 edition of The Salt Lake Tribune stating that the BLM had given approval to Desert Hawk Gold Corp. to start up a cyanide heap-leach mine in the Gold Hill area---extracting the gold and silver.  I am uncertain if actual mining has commenced.   

  

REFERENCES CITED

Ege, C.L., 2005, Selected mining districts in Utah: Utah Geological Survey, Miscellaneous Publication 05-5.

Nelson, M. E., and J.H. Madsen, Jr., 1987, A new Clarendonian (late Miocene) fauna from eastern Nevada: Contributions to Geology, University of Wyoming, v. 25, p. 23-28.

Robinson, J.P., 1993, Provisional geologic map of the Gold Hill quadrangle, Tooele County, Utah: Utah Geological Survey Map 140, scale 1:24,000.