An Amateur Scientist Examines Pegmatitic Biotite Mica
Copyright © 1992-1997 by John Brawley
[Last Update: December 22, 1992]

[Permission hereby granted to copy and disseminate.]

Abstract

Samples of mica (var. biotite) from pegmatites in two states [North Carolina: Spruce Pine district and South Dakota: Harney Peak batholith (Black Hills)] are examined under the microscope. Radioactive element decay chains and alpha particle energies are explored in order to determine possible mechanisms for production of point-source pleochroic radiohalos in the samples. Special attention is paid to "Polonium"-type halos of the series 84Po218, 84Po214, 84Po210.

Not many of the subjects attendant on the creation / evolution "controversy" are accessible to the amateur scientist for direct examination. DNA analysis requires expensive technical equipment, and examining for oneself the extensive fossil record 'in situ' might require a lifetime.

The claims put forth by Dr. Robert V. Gentry, however, seem uniquely suited to direct examination by anyone with access to biotite mica and a decent microscope such as can be begged, borrowed or rented from the local high school science department. I am perhaps lucky that my mother taught high school biology for most of her life, and that upon her passing I obtained her personal 'scope.

Samples require only some knowledge of where they might be found, the means -- vehicle and gas, food and lodging -- to get there, and a small sledgehammer and pocket knife. Labelled plastic sandwich or freezer bags make good sample containers. A slight talent for glib talk (or better: complete honesty), is helpful in explaining why one wishes to enter mines abandoned and ignored for more than forty years -- and which are located primarily on private property. One does not enter dangerous areas to obtain samples, in most cases.

I was first alerted to the "polonium halo problem" via a local electronic bulletin board ('BBS') which carried an "echo" (nationwide message-repeater system) called BioGenesis, in which the creation / evolution "controversy" was being heatedly discussed.

Upon obtaining Dr. Gentry's book, "Creation's Tiny Mystery," I found that there indeed seemed to be a legitimate claim being made: the requirement for long cooling periods (many, many years) in granites, combined with an extremely short half-life for Polonium, made it seem quite impossible for particles of Polonium-218 (half-life around three minutes) to have become entrapped in crystals of biotite which grew slowly to include them. All Polonium-218 must have decayed at least to mass 210 by the time the crystal had solidified sufficiently to retain alpha-particle damage to its crystal lattice.

The suggested decay chain for Polonium is as follows. (I have begun the chain at Radon-222, fifth in the series of alpha particle- emitting daughters of Uranium-238, both for brevity and for another reason which will shortly become clear.)

86 Rn 222 (86 protons, Radon, mass 222) decays in about four days to Polonium-218 with the emission of an alpha particle of 5,486,000 electron volts (5.486 MeV). (Please note this energy value.)

84 Po 218 (84 protons, Polonium, mass 218) decays, through two additional non-alpha-emitting (beta decay) steps involving Lead and Bismuth, over a total of about 45 minutes, to Polonium-214 with the emission of a 6.111 MeV alpha particle.

84 Po 214 (84 protons, Polonium, mass 214, arriving via Lead-214 (27 minutes) and Bismuth 214 (20 minutes)) decays through two additional (and time-consuming) steps taking about 21 years, to Polonium 210, with the emission of a 7.687 MeV alpha particle. This involves the immediate alpha decay (.000164 seconds) of the Po-214 nucleus to Lead 210, which has a half-life of 21 years, then via beta decay to Bismuth 210 with a 5 day half-life, and another beta decay to Po 210. (There is a small chance of the Bismuth 210 appearing in its isomeric form, which has a half-life of three million years.) This Polonium-214 alpha energy is the highest in the Uranium 238 decay chain, and consequently creates the largest, outermost, halo.

84 Po 210 (84 protons, Polonium, mass 210) decays with a half-life of 138 days directly to Lead 206 (stable), emitting an alpha particle of 5,305,000 electron-volts' energy. (Note the close similarity between this energy and that of the decay from Radon 222 to Polonium 218.)

82 Pb 206 (82 protons, Lead, mass 206). End of the line. Stable Lead. No further decay is possible.

My first explanatory hypothesis was that if there were enough Uranium-235 or other fissionable material in the pegmatite, and if there were tiny Lead particles (any stable isotope) also present, then a low- level background flux of neutrons captured by the lead might produce a Polonium-210 halo. The CRC Handbook of Chemistry and Physics' radionuclide tables showed that this process would, in fact, result inevitably in a Polonium atom from Lead-206, with the addition of only four neutrons per atom over geologic time. Interestingly, this would produce Polonium-210 repeatedly, being a cyclic process; Lead plus four neutrons producing Polonium, then the Polonium alpha-decaying back to lead-206. It also, with the addition of two more neutrons during a 'window' of time, could produce outer halos sized very nearly as Polonium-218 and Polonium-214. This was the hypothesis I carried with me to North Carolina on my first sample-gathering trip.

However, on that trip I made a stop at Oak Ridge National Laboratories in Tennessee and talked my way inside, to speak with a Mr. J.K. Dickens, scientist in the electron laboratory, who had worked alongside Dr. Gentry during his stay there. Mr. Dickens pointed out that, while my hypothesis was quite valid from an ideal point of view, there were several "bottlenecks" where an unusually low neutron-capture cross-section would make the transition to Polonium highly unlikely, although not impossible. (Mr. Dickens did give me some encouragement, both by suggesting a way to test for neutron addition / Polonium / Bismuth formation from lead, and by stating, upon seeing my photomicrographs of 'drifts' and 'strings' of halos along cracks and inclusions, "I've never seen anything like that!" I found it significant that one of the people who had been near Dr. Gentry and had seen his work, had "never seen" certain phenomena in the biotite that I had seen and photographed.) [Note: Mr. Dickens also told me a story about the procurement by one of the researchers of radiohalo samples from Madagascar--samples previously possessed by the daughter of Madame Curie and obtained from France. A most interesting story indeed, but beyond the scope of this paper.]

Identification Problems

Dr. Gentry's book contains an excellent section of photomicrographs of various radiohalo types. Bearing in mind the two similar alpha energies (Radon 222 and Polonium 210, noted above), I saw that Dr. Gentry's photographs of Uranium 238 halos, which must contain eight alpha emitting steps, show in all cases only five damage rings. This means that some of the U-238 rings are actually several rings so close to one another that they are microscopically indistinguishable even at powers of 1000X and higher. As it happens, one of those rings which is actually two rings is the ring formed by both Radon 222 and Polonium 210.

It is known that all eight rings are present in a Uranium 238 halo, yet the double ring Rn-222 / Po-210 looks (in all cases I have seen) like only one ring.

If this were so, I thought, then how could identification of halos consisting of only the Polonium isotopes be certain? There could be no way microscopically or even with an ion microprobe to distinguish between a Radon 222 --> Polonium 210 halo and a Polonium 218 --> Polonium 210 halo.

At this point, one of those rare and welcome "Aha!" experiences occurred as I realized that Radon is:

* A gas,

* An inert gas,

* Produced a few atoms at a time in the U-238 decay chain, continuously and steadily over geologic time.

There was therefore no reason to think that Radon manufactured in any nearby Uranium mineral particle (uraninite, betafite, uranophane, etc.) would stay attached to the disintegrating particle; an atom with a filled outer shell would not 'attach' to the biotite crystal's atoms, nor would it be likely to remain attached to the disintegrating Uranium mineral inclusion. Moreover, with about four days to move around as single atoms subject to thermodynamic gas laws, it could wander literally anywhere in the mica permitted by the slightest crack, cavity, lattice discontinuity, or separation between crystal planes, "pushed" along by new Radon atoms forming back 'behind' it in the inclusion.

Preexisting Observational Evidence

My initial microscope exploration of biotite mica (kindly given me by Mike Fix of the physics department of the University of Missouri at St. Louis) had shown many interesting and unusual features not mentioned by Dr. Gentry in his book, among which were cracks and fissures surrounded by faint discolorations of halo width. In a few cases, these crack-following halos were actually double halos, just as if they had been crack-shaped deposits of Polonium at one time. If Radon 222 were migrating, a few atoms at a time, down these cracks, most of which originated at or near large, obviously radioactive mineral inclusions or at the biotite crystal's edges where severe radiation damage was apparent, then such 'crack-halos' would be expected. Moreover, given restrictions in the cracks, and particles of previously-deposited lead 206, I could envision locations along the haloed cracks where Radon 222 might find itself preferentially delayed long enough to decay repeatedly in the same spots, generating spherical halos there. This might account for the many cases of multiple halos I found 'strung out' along the cracks like beads on a chain. (I have some photos of such strings and 'drifts' of halos.) It also occurred to me that there might be electron-based attractions between Polonium, Bismuth, or Lead, formed suddenly as the Radon underwent decay, and Lead atoms previously deposited in these areas. (Lead, like Carbon, has four electrons in its outer shell, thus presumably might have a net attraction for a nearby, suddenly-appearing atom of Polonium, which has six. My knowledge of chemistry is limited, however, so this idea needs further work.)

Since I had been examining mica from an uncertain source, (I had only UMSL's and its source's word that the source was the 'Etta' mine in South Dakota), it became scientifically necessary for me to be able to pin down the exact location from which my samples were obtained, so I packed my truck and left for North Carolina, the closest place where mica mines had existed in profusion in past years. There I obtained very few biotite samples; the Spruce Pine district was a fine source of muscovite (white) mica, but biotite was scarce. (Even so, some halos were observed in this mica. As far as I know, this constitutes the first reporting in the literature of pointlike halos found in muscovite mica.) Two sources near Mars Hill, N.C. did yield large quantities of 'sheet' biotite. However, I have yet to find a single halo in this biotite. Significantly, there is also no evidence whatsoever of radioactivity in this biotite. These two sources, the Roy Young property and two old workings atop Nofat Mountain, perhaps indicate most clearly the relationship between radioactives and radiohalos: no evidence of radioactivity or radioactive inclusions seems also to indicate no halos.

The sparsity of halos in the North Carolina biotite samples drove me to find the 'Etta' mine in South Dakota, and to sample it as well as other mines in the Custer and Keystone areas. This gathering trip was highly successful, and several mines, notably the "Helen Beryl Mine," yielded nice biotite crystals literally peppered with halos of many types. The Etta, Rainbow no.4, and Peerless mines were also very productive. (A 'Mine List' is attached. See Appendix 'A')

In this mica I observed halos which caused me to begin to suspect that not only would precise identification of "Polonium" halos be difficult due to the impossibility of being sure they were not Radon- caused halos, but also there seemed to be some problem merely correctly identifying a two- or three-ring halo which was not actually a Uranium halo either in some early stage of development or produced by a somewhat oversized particle of Uranium mineral. A very dark Uranium halo, if no detail can be distinguished inward of the Polonium-210 / Radon-222 ring (where all the Uranium / Thorium decays are located), cannot be told from a very dark "Polonium-218" halo. They look exactly alike. Only a three- ring "Polonium-218" (or Radon-222) halo which is a) light enough to reveal detail within the innermost ring and b) made by a sufficiently small particle, can be unambiguously identified as such: a light inner halo reveals Uranium / Thorium rings if present, and if the radiocenter is too large, all the inner rings overlap and do not show distinct "ring" structure, yet since both the Po-218 and Po-214 rings are made by much higher energy alphas--thus having much greater range than the inner ring-forming alphas, a Po-214 halo remains a feature of even large- particle Uranium halos. A maximum difference of only 520,000 electron- volts exists between even the farthest-apart inner halos, but between the outermost of these and the Po-214 halo, a difference of 2,200,000 eV exists.

Dr. Gentry notes in his book that it takes about 100 million alpha decays before a halo "initially develops" (CTM, p19), becoming darker after 500 million, and very dark after 1 billion alpha emissions. If it were true that the three-ring, "Polonium-218" halos were actually Radon- 222 halos, it would be difficult also to distinguish between the single, smaller, "Po-210" halos and early Radon halos: I had observed that around some "Po-210"-type halos existed the faintest imaginable outer ring, sized as a Po-214 halo, which disappeared under higher magnification. That is, some Po-210 type halos, viewed at 40, 60, and 100X magnifications, showed an outer Po-214 type ring that was just on the edge of visibility. It was actually a case of "Am I really seeing that?" Yet, going to higher magnification, the outer halo could not be seen at all. This was the case with even Po-214-type outer halos that were definitely there under the lower powers. If these were actually Radon halos in an early stage of development, then while the "Po-210" halo would be visible due to two alphas being employed to cause it (Radon-222 and Po-210), only one alpha each would be available to form the other two rings (Po-218 and Po-214), which might then still be on the edge or below the threshold of visibility. Additionally, the density of the smaller halo would be improved through concentration of damage relative to the larger-area halos. Thus, it would be possible to observe what appeared to be a single, Polonium-210 halo which was actually a two-alpha-produced Radon halo, with the two outer halos (Po- 218 and Po-214) present but still below the level of visibility.

Unlike a "Polonium" halo, which must be formed once in a geologically short time and thereafter merely sit waiting to be found, a Radon-222 halo would be in a state of continuous formation more or less throughout geologic time, without requiring any hydrothermal activity to 'separate' the Polonium isotopes from any Uranium-particle source: gaseous Radon transports itself. Hence, depending on multiple factors such as the configuration of cracks, buildup of Lead particles in them, new cracks or distortions formed under geologic shifting, and other changing conditions, Radon-222 halos might be seen in all conceivable stages of development. Radon halos would be the only types capable of continuing 'migratory' formation, since "Polonium," Uranium, and Thorium halos can only form around particles locked into places in the biotite crystal lattice or transported by subsequent hydrothermal activity.

I have at this point in my work reached an impasse. I have many photos, in both color and black-and-white, of my samples, and I have amassed a small collection of samples labelled and stored. I know where exactly each sample came out of the earth, having scraped the biotite off of the pegmatite surfaces or gathered it from the mine dumps with my own hands. I have examined much of the biotite directly, and have approximately a hundred times as much yet to examine by splitting and observing. I have expended personal funds, and have reached the end of them. I have several proposals for testing the Radon hypothesis, but not yet the means to do them. For example:

1. If it is true that these unambiguous "Polonium-218" (according to Dr. Gentry) halos are actually Radon-222 halos, then it should be possible to statistically determine the relative density of the three rings. If this were done with a through-the-microscope photometer, the inner halo should have a density reading roughly twice that of either of the outer two halos, when adjusted for the difference in their diameters. Visually, this seems to be the case with both Dr. Gentry's own photomicrographs and with my own positively identified three-ring halos. Visual judgement, however, can be wrong.

2. Although I am unfamiliar with scanning electron microscopes, it should be possible to image the general damage in the crystal lattice at each halo's location. If so, then while each of the outer two halos would show a perhaps gaussian 'curve of damage pits' reaching from the inner edge of the halo through the field of alpha-particle hits to the outer edge, the Radon-222 / Polonium-210 ring should reveal either a wider field with a flat extent in the middle, or an actual saddle-shaped distribution of damage pits resulting from the presence of two sets of alpha particle shocks. This might be detectable under electron microscope magnifications, while it is certainly not visible with a standard light microscope.

3. It should actually be possible to reproduce in some way the halos, using clean (halo-free) biotite samples and a source of Radon-222. If a small sealed cell were arranged, with the edge of a sheet of this clean mica sandwiched into its perimeter so that Radon produced by a large sample of Uranium-238 would have access to the ragged edge of the mica, then given enough time, the Radon produced by the Uranium should migrate into the biotite and decay there, reproducing the process hypothesized to occur in the natural pegmatite. The time this would require might be prohibitive, but at least one could generate Radon with a more concentrated and larger sample of Uranium than typically is present as a mineral in the natural state, reducing the time required. This experiment would most closely duplicate the actual conditions forming Radon-222 halos, and would be a definitive test of this hypothesis. (Most of my halos are found around radioactive inclusions in the biotite, and most of the samples of biotite from the Black Hills have their edges peppered with halos, contrary to the information Dr. Gentry reports in his book (CTM, p30).

In Conclusion, I believe that Radon-222 is the most likely candidate for the source of certain "Polonium-218" halos in biotite mica. The process envisioned is most consistent with the data (including some observational data not mentioned by previous researchers), and providentially is unique in its characteristics: Radon is an inert gas, the only gas in the Uranium-238 decay chain, having the thermodynamic ability and more than enough time to migrate about in the mica, a few atoms at a time. Also significant is the apparent impossibility of distinguishing Radon-222 halos from Polonium- 218 halos under the microscope.

This work was done during the months of March-November, 1992, by John Brawley. Both a Bausch and Lomb Student microscope and a Bausch and Lomb professional flat-field microscope capable of 40X through 1500X magnifications, provided by Chris Downs of St. Louis, were used. Samples came from North Carolina near Spruce Pine, and from the Black Hills of South Dakota (Appendix A).

[Note: In South Dakota, measurements of pegmatite gamma radiation were made using an Integral Field Spectrometer ('scintillometer'), EDA model GRS 400, rented from the South Dakota School of Mines in Rapid City.]

This text is copyright (c) 1992 by John Brawley. Permission is hereby granted to copy and distribute freely, in the interests of science, but all rights remain with the copyright holder, his heirs and assigns.

Appendix A (List of source mines for mica used in these observations)

North Carolina: (Spruce Pine District)

* Wiseman Mine, 1 mi. NNE of Minpro.

* "Ed and Will Swain mine" (crest of Nofat Mt.), 1/2 mi. NW of Democrat.

* Sinkhole mine, Bandana district., (The oldest mica mine in NC; this mine was used by the Indians.)

* Bud Phillips' dolomitic marble workings, Bandana district. (Near the Sinkhole mine.)

* "Emerald Village" (the old McKinney mine).

* Hootowl mine, 1/2 mi. N of Crabtree Mountain.

* Chestnut Flat mine, 3/4 mi. E of Bear Creek P.O. (Note: this mine is noted in the referenced source as the mine from which quartz for the 200-inch mirror on Mt. Palomar was taken.)

* Pine Mountain mine (owned by K.T. Feldspar Corp.), 1 mi. N of Minpro.

* "Crabtree Emerald Mine", at end of a BAD road above the McKinney.

* Roy Young property (old Hipp-McSwain mine), 1/2 mi. E of Beech Glen.

* Arrowwood mine, 3 1/4 mi. W of Barnardsville.

* Chrome Spar (Goldsmith) mine, 3 mi. W of Barnardsville.

South Dakota: (Harney Peak batholith, Black Hills)

* Etta mine, NW1/4, sec.16, T.2S, R.6E, 1 mi. S. of Keystone.

* Helen Beryl pegmatite, in sec.7, T.4S, R.4E, approx. 8 mi. SW of Custer.

* Rainbow #4 mine, about 1 mi. E. of the Helen Beryl.

* Hugo mine, within 1/2 mi. of the Etta.

* Peerless mine, 1/4 mi. above the Borglum Museum, Keystone.

* Bob Ingersoll mine nos. 1 and 4, NE1/4NW1/4, sec.6, T.2S, R6E, 2 mi. NW of keystone.

* Homestake Gold Mine, Lead, SD.

* NUTEC Corp. mines: 2 mines located above the Etta, sampled from mica extracted by the company. This mica is the only material not removed by myself.

References

Weast, Robert C., Ph.D. ed.: CRC Handbook of Chemistry and Physics (61st edition); Boca Raton; CRC Press, Inc., 1980.

Gentry, Robert V.: Creation's Tiny Mystery; Knoxville; Earth Science Associates, 1988 (2nd edition).

Olson, J.C.: Economic Geology of the Spruce Pine Pegmatite District, North Carolina (Bulletin No. 43, part I & II, N.C. Division of Mineral Resources); Raleigh, 1944.

Parker, John M. III: Geology and Structure of Part of the Spruce Pine District, North Carolina (Bulletin No. 65, N.C. Division of Mineral Resources); Raleigh, 1952.

Page, Lincoln R. et.al.: Pegmatite Investigations 1942-1945, Black Hills, South Dakota (U.S. Geological Survey Professional Paper 247); Washington, 1953.

South Dakota Geological Survey: Geologic Map of the Black Hills (Educational series map five, after N.H. Darton, USGS); 1951.

General

U.S. Geological Survey: Topographic maps in the series 15 and 7 1/2 minutes, various, covering both locations.

Acknowledgements

In Saint Louis:

* Mike Fix, Physics department, University of Missouri at St. Louis: for the first radiohalo-containing biotite samples, for information and advice, and for chats and equitable sample trades.

* Walt Stumper, System Operator, Origins Talk electronic bulletin board system, and librarian, Missouri Association for Creation: for my copy of "Creation's Tiny Mystery" and for friendly assistance at all times.

* Dr. David N. Menton, professor, Washington University: for encouragement and friendly debate.

In North Carolina:

* Carl E. Merschat, Area Geologist, N. C. Geological Survey, Asheville: for extensive and excellent help in locating likely sources of biotite, and for providing maps and advice from his personal experience in the area. Mr. Merschat was helpful beyond all expectation.

* Bud Phillips, owner, Mitchell Lumber Company: for kind and personal help and advice, for samples, and for permission to hunt mica on his dolomitic marble workings in the Bandana District. Mr. Phillips is a local expert on mines and minerals, and an impressive individual.

* Mr. J.K. Dickens, scientist, Oak Ridge National Laboratories: for a discussion of radiohalos and Dr. Gentry's work while there, and for advice and help on the neutron-addition-to-Lead hypothesis.

* David Merrick, mineralogist, FELDSPAR Corp.: for permission to collect samples in the Wiseman mine.

* Roy Young, resident, Mars Hill: for permission to collect on his property, where the old Hipps-McSwain mine is located. This mine yielded the largest and most lovely samples of biotite I recovered. It appears, however, to be utterly devoid of halos.

* Mars Hill College, Mars Hill: for permission to camp in the parking lot.

In South Dakota:

* Tom Hack and Michael Cepak, Office of Minerals and Mining, Pierre: for advice and information on the Black Hills area, and for contact names and phone numbers of mine property owners.

* South Dakota School of Mines: for rental of a Field Scintillometer, and for advice and cooperation.

* Ray Aldritch, (of Gunderson, Farrar, Aldritch and DeMersseman, representing Harold Shafer, owner) Rapid City: for permission to enter and workcamp on the Bob Ingersoll mine property.

* Mrs. Laura L. Pankratz, Borglum Historical Center, Keystone: for permission to collect on the Peerless mine property (currently owned by Dr. Pankratz), and for her kind and friendly personal attention.

* Gene Kuhnel, owner, the Rock Shed: for permission to collect at the Etta Mine.

* Homestake Gold Mine, Lead: for drill core samples and information on biotite in the Northern Black Hills.

* Mr. Alexander, owner, Hugo mine: for personal attention and permission to search for samples in the mine.

I would like to express my appreciation also to all those individual residents of North Carolina who gave me assistance in one way or another. These people demonstrated true Southern hospitality, and were friendly and cooperative almost without exception. I met with no resistance of any kind, except for the managers at K.T. Feldspar, who were singularly uncooperative, and the reluctantly helpful operators from UNAMIN corporation, who expressed complete astonishment at my appearance (via an old road marked on the 1944 maps) in the offices of their high-security mining operation and could not wait to get me the hell off their property.

The people of the Black Hills region also deserve my thanks, for once I made it clear that I was not a tourist (Mount Rushmore; July), they gave me every possible assistance.

A special note of thanks goes to Chris Downs, who provided the Bausch and Lomb flat-field microscope whose use was so critical to the ability to photomicrograph many of the samples used in this study.

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