ALUM MINERALS, ELEGANT TROGANS, AND SHAVING CUTS

An Elegant Trogan.  Photo Public Domain and courtesy of Dominic Sherony.

My previous posting was on the mineral halotrichite, a hydrated iron sulfate with long wispy crystals or tuffs as a common habit.  I also, several years ago, purchased a mineral box containing halotrichite crystals.  I remember the specimen cost a buck and was covered with a thick layer of dust so I brought it home but dare not blow away too much dust as the crystals were mostly loose and on the surface of an unknown matrix.  But in this time of self-quarantine I have been taking a second peek at many of the mineral specimens stored in the drawers.  So, out popped this specimen labeled: Halotrichite, Karshaw (sic. Harshaw) District, Chief Mine, Coll. 1971, FitsHue Collection. I knew about the Harshaw Mining District mainly due to the Japan Law quartz crystals collected from Washington Camp mining area.  In fact, the entire Patagonia and neighboring Santa Rita Mountains are checked full of old mines and prospecting holes.  I also have camped at Patagonia Lake State Park with two memories of the area: 1) I spotted my first and only specimen of the Elegant Trogan [Trogon elegans]; and 2) in asking directions to the Washington Camp I was warned by locals not to drive there alone, and to travel armed.  It appeared that drug smugglers were in the area.  So, I switched from minerals to bird watching and especially was interested in the Trogan since the Audubon Guide to North American Birds noted “Since the 1890s the possibility of seeing a trogon has lured birdwatchers to southern Arizona. With its brilliant metallic colors and odd croaking call, the Elegant Trogon brings an exotic touch to the wooded canyons and streamside sycamores where it lives. The observer who finds one may get to watch it at leisure: rather sluggish, the trogon may sit upright on one perch for several minutes.”  Trogans are tropical birds but a few migrate north to breed (April-September) in the sycamore canyons of extreme southern Arizona, especially in the Patagonia, Huachuca (Ramsey Canyon) and Santa Rita Mountains (Madera Canyon).  They are sort of a Holy Grail to dedicated bird watchers.  I was honored to be a chosen one and stand under a tree and observe and chat with the fellow for 10 minutes until I quietly departed.  It certainly was the highlight of my meager birding career.


OK, back to the halotrichite, which really doesn’t look like halotrichite--at least to me.  According to MinDat halotrichite is not known from the Chief Mine although Anthony and others (1993) noted its presence. The polymetallic (but mostly copper) Chief Mine is located as one of a group of 12 claims crowded together in Alum Canyon.  It was a small mine and evidently has not been active in the last 100 years or so; no production records were located.  Its next-door neighbor, the World’s Fair Mine, also was in Alum Canyon and was a much larger producer (copper) and MinDat lists 56 valid minerals known from the Mine, including an isolated nodular specimen of halotrichite.  However, there are other photos in MinDat of what is described as Alum Group minerals, a generic name for hydrated aluminum alkalic metal sulfate [XAl(SO₄)₂-12H₂O]. A “dead ringer” photo in MinDat was a “white fibrous alum group mineral collected by Rolf Luetcke at a small tunnel off Alum Gulch”


Most of the mining in the Harshaw District is from copper minerals disseminated in a Tertiary rhyolite and/or lodes/veins of ore along fault fissures and breccia zones in limestones.  What is really interesting is a statement by Schrader and others (1915): “In Alum Canyon, on the southwest, the weathered surface of the rock and the alluvial gravels derived from it are coated with efflorescence and incrustations of alum, some of whose constituents seem to be derived from the pyritic content of the rock through oxidation.” This description would seem to indicate the alum formed post-mining.  So, I am calling this specimen of white fibers from Alum Gulch (maybe, maybe not the Chief Mine) an Alum Group Mineral.

Photos (~4000 Kelvin) of fragile fibers of an Alum Group mineral from Alum Gulch, Harshaw District, Arizona.  Width FOV ~

And, what are Alum Group Minerals?  The generic chemical formula for Alum Group Minerals is XAl(SO₄)₂-12H₂O where X is usually an alkali metal cation with an oxidation state of 1+, usually sodium or potassium but ammonia, titanium or even cesium are available.  Those cations bond with an aluminum cation with an oxidation state of 3+, or occasionally bond with 3+ chromium, cobalt, iron or manganese.  Together those cations then combine with the sulfate radical, SO₄, and lots of water H₂O. 

Photomicrographs (LED ~5600 Kelvin): Fibers of Alum Group mineral from Alum Gulch.  Width FOV ~ 

Alum minerals most common in nature are referred to as Alum-K and Alum-Na. It is really tough to distinguish between these two minerals without some electronic gizmos---at least for me.  Both are soft at Mohs 2-3, form small, vitreous crystals, or fibrous mats, or are massive/granular.  Some crystals are clear and transparent while others are white and opaque.  Both are members of the Isometric Crystal System; however, MinDat noted that crystals are octahedral if they precipitate from pure water but are cubic if they precipitate from an alkaline solution. It appears most descriptions of mineral producing localities use the term Alum Group Minerals although most of these minerals are probably Alum-K.   


There are a couple of different alum minerals that have better mineral names: 1) lanmuchangite, known from two localities, where titanium with an oxidation state of 1+ substitutes for sodium or potassium; and 2) tschermigite with ammonia, NH₄, acting as the monovalent cation.

Natural alum minerals are usually formed as a precipitate around volcanic fumaroles/vents, burning coal beds, or where iron sulfide and potassium/sodium minerals can oxidize.


 A large number of “alum group” minerals are now produced synthetically and used in industry, and alum may be produced from rocks/minerals by adding sulfuric acid to leucite, alunite, bauxite ore, or kaolinite. We know refined alum for its place in the spice rack (alum-K) where my mother used it to crisp home-canned dill pickles. My father had his own use for alum for when he cut himself shaving, he dabbed the cut with a “styptic pencil” (alum-NH₄).   Commercially, alum is used as a flocculating agent in water-purification plants, to size paper, as a binder in dyes, and as an ingredient in baking powder (among the many uses).


Parents of children needing a science project know about growing large, colored (food coloring), octahedral crystals of alum when seed crystals are tied to a thread and suspended in a saturated solution.  They are quite beautiful!

I found USGS Bulletin 582 by Schrader and others (1915) to make fascinating reading, all 372 pages. One of the best sections is his quote about some of the items in a “prospector’s kit” that were used to test for the presence of alunite, an alum mineral:

Boil the powdered sample with water or with hydrochloric acid for several minutes. After allowing the powder to settle pour off the liquid and repeat the operation to insure the removal of all soluble sulphates. Dry the powder and heat to a dull red. Again boil in water, and after settling pour off some of the clear liquid. To this add a small fragment or a solution of barium chloride. If the mineral is alunite a heavy white precipitate will form. To be sure that the water used in this test does not contain sulphates in solution it should be tested with barium chloride, and if it gives a marked precipitate it can not be used. For this test all that is required that is not included in a miner's or prospector's outfit is a little barium chloride, which can be carried in a small bottle or cartridge.


Do modern rockhounds, or even prospectors, have their own chemical lab in their “prospector’s kit”?

REFERENCES CITED

Anthony, J.W., Williams, S.A., Bideaux, R.A., Grant, R.W., 1995, Mineralogy of Arizona, Third Edition: University of Arizona Press, Tucson, Arizona.


Schrader, F.C., J.M. Hill, 1915, Mineral deposits of the Santa Rita and Patagonia Mountains, Arizona, United States Geological Survey: USGS Bulletin 582.

FOR THOSE INQUIRING MINDS

A styptic pencil is an antihemorrhagic agent — simply put, it helps constrict blood vessels so they’ll stop bleeding. It’s most commonly used to treat small wounds and cuts on the face and body. The main ingredient in a styptic pencil is anhydrous (the NH₄ monovalent cation) aluminum sulfate; an agent that restricts blood flow, allowing a cut to close quickly.


And who are the inquiring minds?  Ask Albert Einstein: "I have no special talents. I am only passionately curious." Children are such curious creatures, as are adults that retain an enquiring mind. They explore, question, and wonder, and by doing so, learn. When they are curious about something new, they want to explore it. And while exploring they discover. Through discovery, they learn. This positive cycle of learning is fueled by curiosity and the pleasure that comes from discovery and mastery.