Wikipedia

Pleochroic halo: Difference between revisions

Browse history interactively
← Previous edit
Content deleted Content added
VisualWikitext
m Vsmith moved page Radiohalo to Pleochroic halo over redirect: Valid scientific term : radiohalo is most commonly used by those promoting religious views
mNo edit summary
 
(41 intermediate revisions by 17 users not shown)
Line 1:
{{Short description|Geological phenomenon}}
{{about|the [[geophysics|geophysical]] phenomenon|the [[astronomycreationist interpretation|Robert V. Gentry|the astronomical]] phenomenon|radio halo}}
[[File:Dark crown.JPG|thumb|RadiohalosPleochroic halos around crystals of [[Zircon|zirconszircon]]s in a sample of [[biotite]]]]
A '''Radiohalospleochroic halo''', or '''pleochroic halosradiohalo''', areis a microscopic, spherical shellsshell of discolouration ([[pleochroism]]) within minerals such as [[biotite]] that occuroccurs in [[granite]] and other [[igneous rocks]]. The shellshalo areis a zoneszone of radiation damage caused by the inclusion of minute [[radioactive]] crystals within the host crystal structure. The inclusions are typically [[zircon]], [[apatite]], or [[titanite]] which can accommodate [[uranium]] or [[thorium]] within their [[crystal structure]]s .<ref>{{harvcite book | last=Faure |first=Gunter |title=Principles of Isotope Geology |year=1986 |publisher=Wiley |pages=354–355 }}.</ref> One explanation is that the discolouration is caused by [[alpha particle]]s emitted by the nuclei; the radius of the concentric shells are proportional to the particleparticles's energy .<ref>{{harvcite journal |first1=G.H. |last1=Henderson |first2=S. |last2=Bateson |title=A Quantitative Study of Pleochroic Haloes, I |journal=Proceedings of the Royal Society of London A |year=1934 |volume=145 |pages=563–581 |issue=855 |doi=10.1098/rspa.1934.0120 |jstor=2935523 |bibcode = 1934RSPSA.145..563H |doi-access=free }}.</ref>
 
==Production==
[[Uranium]]-238]] follows a [[decay chain|sequence of decay]] through [[thorium]], [[radium]], [[radon]], [[polonium]], and [[lead]]. These are the alpha-emitting [[isotope]]s in the sequence. (Because of their continuous energy distribution and greater range, [[beta particle]]s cannot form distinct rings.)
 
{|class="wikitable" style="text-align:center"
|-
! Isotope !! [[Half-life]] !! Energy in MeV
|-
|U-238||{{val|4.47|e=9}} years||4.196
Line 14 ⟶ 15:
|U-234||{{val|2.455|e=5}} years||4.776
|-
|Th-230||7540075,400 years||4.6876
|-
|Ra-226||15991,599 years||4.784
|-
|Rn-222||3.823 days||5.4897
Line 29 ⟶ 30:
|}
 
The final characteristics of thea pleochroic radiohalohalo depends upon the initial isotope, and the size of each ring of a radiohalohalo is dependent upon the alpha decay energy. A radiohalopleochroic halo formed from U-238 has theoretically eight concentric rings, with five actually distinguishable under a lighted microscope, while a radiohalohalo formed from polonium has only one, two, or three rings depending on which isotope is the starting material is.<ref>{{harvcite journal |Webertitle=Halos und weitere radioaktive Erscheinungen im Wölsendorfer Fluorit (in German) |journal=Der Aufschluss |volume=61 |pages=107–118 |year=2010 |last=Weber |first=B. |url=http://www.vfmg.de/aufschluss_2-2010_Weber.htm }}.{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> In U-238 haloes, [[Uranium-234|U-234]], and [[Radium-226|Ra-226]] rings coincide with the [[Thorium-230|Th-230]] to form one ring; [[Radon-222|Rn-222]] and [[Polonium-210|Po-210]] rings also coincide to form one ring. These rings are indistinguishable from one another under a lightedpetrographic microscope .<ref>{{harvcite journal |last=Pal |first=Dipak C. | title=Concentric rings of radioactive halo in chlorite, Turamdih uranium deposit, Singhbhum Shear Zone, Eastern India: a possible result of 238U chain decay |journal=Current Science |year=2004 |volume=87 |issue=5 |pages=662–667}}.</ref>
 
==CreationismReferences==
{{Reflist}}▼
 
===Further reading===
[[Young Earth creationism|Young Earth creationist]] [[Robert V. Gentry]] believes that PO-218 radiohalos in granite, where there are apparently no preceding U-238 halos, could not have been formed in molten rock which took many millennia to cool. He instead claims that such rock must have been created instantaneously containing polonium inclusions and that the halos arose from Po-218 alone (rather than U-238 leading to PO-218) decaying with a half-life of 3 minutes.{{harv|Gentry|1992}} However, Gentry's polonium halos are found along microscopic cracks in rocks that also contain uranium halos {{harv|Wakefield|1988}}{{harv|Collins|1997}} and Po-218 is also a decay product of [[radon]] which as a gas can be given off by a grain of uranium in one part of the rock and migrate to another part of the rock to form a uraniumless halo.{{harv|Baillieul|2005}}{{harv|Brawley|1992}}
*#{{citationcite book |first=L.G. |last=Collins |chapter-url=http://www.csun.edu/~vcgeo005/revised8.htm |contributionchapter=Polonium Halos and Myrmekite in Pegmatite and Granite |title=Expanding Geospheres, Energy And Mass Transfers From Earth’sEarth's Interior |pages=128–140 |editor=Hunt, C. W. |editor2=Collins, L. G. |editor3=Skobelin, E. A. |publisher=Polar Publishing Company |publication-placelocation=Calgary |year=1997}}.▼
 
*#{{citationcite journal |first1=S.A. |last1=Durrani |authorlink2author-link2=John H. Fremlin |first2=J.H. |last2=Fremlin |title=Polonium Haloes in Mica |journal=Nature |publication-date=October 1979 |volume=278 |issue=5702 |pages=333–335 |doi=10.1038/278333a0 |year=1979 |last3=Durrani |first3=S. A. |bibcode = 1979Natur.278..333H |s2cid=4260888 }}.▼
==Citations==
*#{{citationcite journal |first1=G.H. |last1=Henderson |first2=S. |last2=Bateson |title=A Quantitative Study of Pleochroic Haloes, I |journal=Proceedings of the Royal Society of London A |year=1934 |volume=145 |pages=563–581 |issue=855 |doi=10.1098/rspa.1934.0120 |jstor=2935523 |bibcode = 1934RSPSA.145..563H |doi-access=free }}.▼
▲{{Reflist}}
#{{cite journal |doi=10.1098/rspa.1939.0143 |title=A quantitative study of pleochroic haloes. V. The genesis of haloes |journal=Proceedings of the Royal Society of London A |volume=173 |issue=953 |pages=250–264 |year=1939|bibcode=1939RSPSA.173..250H |doi-access=free |last1=Henderson |first1=G. H. }}
*{{citation|first=T.A.|last=Baillieul|url=http://www.talkorigins.org/faqs/po-halos/gentry.html|title="Polonium Haloes" Refuted: A Review of "Radioactive Halos in a Radio-Chronological and Cosmological Perspective" by Robert V. Gentry|date=2001–2005|publisher=[[TalkOrigins Archive]]}}
#{{RubberBible82nd}}
*{{citation|url=http://www.talkorigins.org/faqs/po-halos/violences.html|title=Evolution's Tiny Violences: The Po-Halo Mystery|first=J.|last=Brawley|year=1992|publisher=[[TalkOrigins Archive]]}}
#{{cite journal |doi=10.1126/science.180.4092.1272 |title=Polonium Radiohalos: An Alternate Interpretation |journal=Science |volume=180 |issue=4092 |pages=1272–1274 |year=1973 |last1=Moazed |first1=C. |last2=Spector |first2=R. M. |last3=Ward |first3=R. F.|pmid=17759119 |bibcode=1973Sci...180.1272M |s2cid=32535868 }}
▲*{{citation|first=L.G.|last=Collins|url=http://www.csun.edu/~vcgeo005/revised8.htm|contribution=Polonium Halos and Myrmekite in Pegmatite and Granite|title=Expanding Geospheres, Energy And Mass Transfers From Earth’s Interior|pages=128–140|editor=Hunt, C. W. |editor2=Collins, L. G. |editor3=Skobelin, E. A.|publisher=Polar Publishing Company|publication-place=Calgary|year=1997}}.
#{{cite journal |doi=10.1126/science.246.4926.107 |title=Giant Radiation-Induced Color Halos in Quartz: Solution to a Riddle |journal=Science |volume=246 |issue=4926 |pages=107–109 |year=1989 |last1=Odom |first1=A. L. |last2=Rink |first2=W. J.|pmid=17837769 |bibcode=1989Sci...246..107L |s2cid=1639793 }}
▲*{{citation|first1=S.A.|last1=Durrani|authorlink2=John H. Fremlin|first2=J.H.|last2=Fremlin|title=Polonium Haloes in Mica|journal=Nature|publication-date=October 1979|volume=278|issue=5702|pages=333–335|doi=10.1038/278333a0|year=1979|last3=Durrani|first3=S. A.|bibcode = 1979Natur.278..333H }}.
*#{{citationcite journal |first=C |last=Schnier |title= Indications for the existence of superheavy elements in radioactive halos |journal=Journal of Radioanalytical and Nuclear Chemistry|publication-date=August 2002|volume=253 |issue=2 |pages=209–216 |doi=10.1023/A:1019633305770 |year=2002|s2cid=120109166 }}.▼
*[[C. Leroy Ellenberger|Ellenberger, C.L.]], with reply by Gentry, R.V. 1984. "Polonium Halos Redux," ''Physics Today''. December 1984. pp.&nbsp;91–92
#{{cite journal |doi=10.1029/EO060i033p00617 |title=Polonium halos and geochronology |journal=Eos, Transactions American Geophysical Union |volume=60 |issue=33 |pages=617–618 |year=1979 |last1=York |first1=Derek|bibcode=1979EOSTr..60..617Y }}
*[[C. Leroy Ellenberger|Ellenberger, C.L.]] 1986. "Absolute Dating," unanswered surrebuttal to Gentry, ''Physics Today''. March 1986. pp.&nbsp;152, 156
*{{citation| last=Faure|first=Gunter |title=Principles of Isotope Geology|year=1986|publisher=Wiley|pages=354–355 }}.
*{{citation|last=Gentry|first=R.V.|title=Giant Radioactive Halos: Indicators of Unknown Alpha-Radioactivity?|journal=Science |publication-date=August 1970 |year=1970|volume=169|pages=670–673|url=http://www.halos.com/reports/science-1970-giant-halos.pdf|pmid=17791843|issue=3946|doi=10.1126/science.169.3946.670|bibcode = 1970Sci...169..670G }}.
*{{citation|last=Gentry|first=R.V.|title=Spectacle Haloes|journal=Nature|publication-date=October 1975| year=1975|volume=258|pages=269–270|bibcode = 1975Natur.258..269G |doi = 10.1038/258269c0|issue=5532}}.
*{{citation|last=Gentry|first=R.V.|title=Radioactive Halos|journal=Annual Review of Nuclear Science |publication-date=October 1973|volume=23|issue=1|pages=347–362|doi=10.1146/annurev.ns.23.120173.002023|year=1973|bibcode = 1973ARNPS..23..347G }}.
*{{citation|last=Gentry|first=R.V.|title=Radiohalos in a Radiochronological and Cosmological Perspective|journal=Science |publication-date=October 1974 |year=1974| volume=184|pages=62–66|url=http://www.halos.com/reports/science-1974-radiohalos.pdf|pmid=17734632|issue=4132|doi=10.1126/science.184.4132.62|bibcode = 1974Sci...184...62G }}.
*{{citation|last=Gentry|first=R.V.|title=Creation's Tiny Mystery|year=1992|publication-date=2004|publisher=Earth Science Associates|url=http://www.halos.com/book/ctm-toc.htm}}.
▲*{{citation|first1=G.H.|last1=Henderson|first2=S.|last2=Bateson|title=A Quantitative Study of Pleochroic Haloes, I|journal=Proceedings of the Royal Society of London A|year=1934|volume=145|pages=563–581|issue=855|doi=10.1098/rspa.1934.0120|jstor=2935523|bibcode = 1934RSPSA.145..563H }}.
*Henderson, G. H., "A quantitative study of pleochroic halos: V, The genesis of halos", ''Proc. Roy. Soc.'' A, 173:250–264, 1939.
*Henderson, G. H., and F. W. Sparks, "A quantitative study of pleochroic halos, IV, New types of halos", ''Proc. Roy. Soc.'' A, 173:238–249, 1939.
*{{Citation|author=Lide, David R. (Ed.)|title=CRC Handbook of Chemistry and Physics, 82nd Ed.|location=London|publisher=CRC Press|year=2001|isbn=0-8493-0482-2}}
*Moazed, Cyrus; Richard M. Spector; Richard F. Ward, 1973, Polonium Radiohalos: An Alternate Interpretation, Science, Vol. 180, pp.&nbsp;1272–1274.
*Odom, L.A., and Rink, W.J., 1989, "Giant Radiation-Induced Color Halos in Quartz: Solution to a Riddle", ''Science'', v. 246, pp.&nbsp;107–109.
*Osmon, P., 1986, "Gentry’s pleochroic halos: Creation/Evolution," Newsletter, Feser, Karl D., Editor, v. 6, no. 1, Concord College, Athens, West Virginia
*{{citation|last=Pal|first=Dipak C.|url=http://www.ias.ac.in/currsci/sep102004/662.pdf|format=PDF|series=87| title=Concentric rings of radioactive halo in chlorite, Turamdih uranium deposit, Singhbhum Shear Zone, Eastern India: a possible result of 238U chain decay|journal=Current Science|publication-date=10 September 2004|year=2004|volume=n5|pages=662–667}}.
*Schadewald, R., 1987. "Gentry’s tiny mystery, Creation/Evolution" Newsletter, Fezer, Karl D, Editor, v. 4, no. 2 & 3. Concord College. Athens. West Virginia, p 20.
▲*{{citation|first=C|last=Schnier|title= Indications for the existence of superheavy elements in radioactive halos|journal=Journal of Radioanalytical and Nuclear Chemistry|publication-date=August 2002|volume=253|issue=2|pages=209–216|doi=10.1023/A:1019633305770|year=2002}}.
*{{citation|last=Wakefield|first=J. R.|year=1988|title=The geology of 'Gentry’s Tiny Mystery'|journal=Journal of Geological Education|volume=36|pages=161–175|url=http://www.csun.edu/~vcgeo005/gentry/tiny.htm}}.
*Wakefield, J. R., 1987–88, "Gentry’s Tiny Mystery - unsupported by geology," Creation/Evolution, v. 22, p.&nbsp;13–33.
*{{cite journal|title=Halos und weitere radioaktive Erscheinungen im Wölsendorfer Fluorit (in German)|journal=Der Aufschluss|volume=61|pages=107–118|year=2010|last=Weber|first=B.|url=http://www.vfmg.de/aufschluss_2-2010_Weber.htm|ref=harv}}{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }}
*York, D., 1979, Pleochroic Halos and Geochronology, EOS, v. 60, no. 33, pp.&nbsp;617–618, Aug. 14, 1979 (publication of the American Geophysical Union).
 
==External links==
* [http://www.csun.edu/~vcgeo005/gentry/tiny.htm ''Geology of Gentry's "Tiny Mystery"''], J. Richard Wakefield, ''Journal of Geological Education'', May 1988.
* [http://www.talkorigins.org/faqs/po-halos/default.htm Polonium Halo FAQs], [[TalkOrigins Archive]]
* [https://web.archive.org/web/20060625082326/http://www.answersincreation.org/bookreview/tnb/thousands_not_billions_chapter5.htm ''Thousands ... Not Billions'' book review], [[Answers in Creation]]
 
[[Category:Radioactive gemstones]]
[[Category:Radiometric dating]]
[[Category:Creation scienceLead]]
[[Category:Polonium]]
[[Category:Radon]]
[[Category:Radium]]
[[Category:Thorium]]
Retrieved from "https://en.wikipedia.org/wiki/Pleochroic_halo"