WHELANITE, STRINGHAMITE AND CALLAGHANITE: THE UTAH TRILOGY

As most readers know, I was a lost Kansas boy when I headed to Utah in September 1967 with the intent of entering graduate school and completing a doctorate in geology.  I had just graduated with an A.M. from the University of South Dakota, married a SoDak girl, packed the ole Pontiac, and headed west.  Two small town kids sort of frightened about the future.  In retrospect, “things” and events turned out OK as I completed the degree and we recently celebrated 50 years together.

Everything we owned was packed into the Pontiac, ready to sustain us as we embarked on our new life in Salt lake City.  No room in the trunk, or the back seat, so note the spare tire lashed to the top of the rooftop carrier.  Not much money in our pockets (hardly any) but lots of enthusiasm and a spirit of "heading west to the mountains."

I noted in a previous Blog Postings that my dissertation advisor, Lee Stokes, sort of forced me (or at least strongly encouraged) to head out of the Geology Department and meet other College faculty members.  In that particular period of time the area of geology had three separate departments, each with a chair and faculty:  Geology, Geophysics, and Mineralogy.  These departments were then grouped with others into the College of Mines and Mineral Industries.  The “others” included meteorology and some mining and mineral engineering departments (my mind failed here).  Somewhere around 1968 the three “geology” departments became a single department, Geology and Geophysics, and Eugene Callaghan served as the first Chair.  In 1988 the group became the College of Mines and Earth Sciences with departments of Atmospheric Sciences, Geology and Geophysics, Metallurgical Engineering, and Mining Engineering. 

I bring up this brief history since one (of three) of the mineralogists that I visited in the early days was Dr. Bronson Stringham, the Department Chair of Mineralogy whose namesake is the mineral stringhamite, a hydrated calcium copper silicate [CaCuSiO₄-H₂O]; see Blog Posting Nov. 26, 2014. 

Blue stringhamite (S) from the Christmas Mine along with xonotlite (X: CaSi₆O₁₇(OH)) and grossular garnet (G: Ca₃Al₂(SiO₄)₃).  Width of photomicrograph ~9 mm indicating individual crystals of stringhamite are submillimeter in size.  Collecting label states: Collected in late 1970s by J. Hediz.

The second mineralogist was Dr. Callaghan (see above), a world famous economic geologist, whose namesake is the mineral callaghanite, a hydrated copper magnesium carbonate [Cu₂Mg₂(CO₃)(OH)₆-2H₂O]: see Blog Posting May 5, 2014.  

Incrustation of callaghanite from Sierra Magnesite Mine, Nye County, Nevada.  Width of photomicrograph~1.1 cm.

Reverse of callaghanite specimen shows hundreds of submillimeter light blue botryoids of McGuinessite:

(Mg,Cu)₂(CO₃)(OH)₂

The third mineralogist who received a visit was Dr. James Whelan.  It was perhaps the most interesting conversation since Dr. Whelan’s office was crammed with fascinating mineral and rock specimens that he brought out to show a somewhat intimidated graduate student interested in soft rocks and fossils.  A few years ago, Dr. Whelan was honored with the naming of the mineral whelanite.  I have been looking for specimens of this rare Cu₂Ca₆[Si₆O₁₇(OH)](CO₃)(OH)₃(H₂O)₂ since reading the “discovery” article (Kampf, 2012), wanting to match it with my specimens of callaghanite and stringhamite.  So, at the recent Denver Rock and Mineral Show I was ecstatic to spot two specimens of whelanite.  Wow, I grabbed them up to complete my trilogy.  I found it interesting that all three mineralogists appeared at about the same time in my early geological life----and promptly disappeared as I immersed myself into the world of stratigraphy, paleontology and academic administration.  They reappeared after “retirement” and I began to collect minerals, and started thinking about those good years of graduate school 50 years ago.  Remembering, as John Adams noted: Old minds are like old horses; you must exercise them if you wish to keep them in working order. 

Whelanite is one of those minerals that is difficult for me to completely understand, and has a chemical formula that I could never memorize if needed for a mineralogy class (luckily it had not been discovered in 1964), and the subscripts are really difficult for me to type: Cu₂Ca₆[Si₆O₁₇(OH)](CO₃)(OH)₃(H₂O)₂. To add to the confusion, whelanite was first collected in 1969 (undescribed silico-carbonate of copper and calcium found with the type specimen of stringhamite; Hindman, 1976) and was approved as a new mineral by the International Mineralogical Association in 1977; however, a description was never published until 2012 (Kampf and others). It seems as if researchers could not quite determine the internal structure via electronic gizmos, e.g. XRD, Raman Spectroscopy. Scanning Electron Microscopy, etc.  After reading the 2012 paper several times, I greatly appreciated their efforts and fully understand why Hindman had difficulty in the 1960s and 1970s.

 

Sprays of blue whelanite from the Christmas Mine, each about 1.8 mm in width, situated on white fibers of tobermorite (Ca₅Si₆O₁₆(OH)₂-nH2O) and grossular garnet.

Whelanite generally, at least on my specimens, occurs as radial aggregates of flattened and elongated lath-like crystals, or as “clumps of the laths that appear as splinters. The crystals are quite vitreous in luster and are some shade of blue—turquoise to greenish to pale.  The tiny crystals are transparent and have a pale blue streak.  The hardness is somewhere around 2.5 (Mohs) and the laths can be carefully manipulated to indicate flexibility.  Whelanite is one of those minerals that seems like once you see it, you will remember it (but not the chemical formula).

Whelanite was first discovered/collected/reported (1969) from the Bawana Mine (open pit), Rocky District, Beaver County (four miles northwest of Milford), Utah.  Kampf and others (2012) noted that “whelanite is found as a late-stage phase in copper-rich, calc-silicate skarn assemblages. [Skarns are generally thought of as an assemblage of calc-silicate minerals, along with garnet and pyroxenes, that formed near the intersection of igneous plutons and limestones that also contain ore minerals]. At the Bawana mine, the mineral occurs with kinoite [calcium copper silicate; see Blog Posting November 26, 2014], stringhamite (Hindman 1976) and thaumasite [copper silicate hydrate] on rock containing diopside [magnesium calcium silicate, a pyroxene], garnet [grossular–andradite; calcium aluminum silicate], goethite [iron], magnetite [iron], and tenorite [iron] [and chrysocolla (copper)].” The Bawana was mined during the time period of 1962-1967 with the target mineral copper produced from a copper and magnetite bearing skarn deposit.  The Rocky District, and adjacent Beaver Lake District, first saw mineral production in the early 1870s with most ore tonnage extracted from the Old Hickory Mine and the OK Mine.  By the early 1960s aero- and ground-magnetic surveys indicated the presence of skarn deposits under shallow alluvial cover and led to the Bawana, Maria and Hidden Treasure mines.  The Rocky and Beaver Lake Districts stopped all production in1974 (Wray, 2006). 

Kampf and others (2012) also confirmed the presence of whelanite at the Christmas Mine in Pinal County, Arizona, and the Sunrise copper project, Nelson Range, Inyo County, California. There is a questionable occurrence at the Crestmore Quarry near Riverside, California.

My specimens of whelanite came from the famous Christmas Mine in Pinal County, Arizona.  Again, the ore producing areas are skarn deposits where Paleozoic limestones have come in contact a quartz diorite intrusion of Tertiary age.  The major ore targets were copper, gold and silver although there were minor amounts of molybdenum, bismuth, lead, zinc, beryllium, scheelite, iron and garnet abrasive (Peterson and Swanson, 1956). The Christmas Mine is perhaps best known for the beautiful specimens of blue kinoite on clear crystals of hydroxyapophyllite (see Blog Posting November 26, 2014). 

I am pleased to finally finish my quest of acquiring mineral specimens honoring three Utah mineralogists who wandered into my early geological training---although I never wandered into their classroom (too frightened of the subject).  My dissertation advisor, Lee Stokes, was honored with the naming of a small Jurassic tyrannosauroid dinosaur as Stokesosaurus clevelandi. 

  

REFERENCES CITED

Kampf, R.A., S.J. Mills, S. Merlino, M. Pasero, A.M. McDonald, w.B. Wray, J.R. Hindman, 2012, Whelanite Cu₂Ca₆[Si₆O₁₇(OH)](CO₃)(OH)₃(H₂O)₂, an (old) new mineral from the Bawana mine, Milford, Utah: American Mineralogist, Volume 97.

  

Peterson, N.P., and  R.W. Swanson, 1956, Geology of the Christmas Copper Mine:  U.S. Geological Survey Bulletin 1027-H.

Wray, W.B., 2006, Mines and Geology of the Rocky and Beaver Lake Districts, Beaver County, Utah in R.L. Bon, R.W. Gloyn, G.M. Par, Eds.: Mining Districts of Utah: Utah Geological Association Publication 32.