Editing Demantoid (section)

==Horsetails==

Russian demantoid often contain inclusions of [[chrysotile]],<ref name="HorseTail">{{cite web|author=Robert Weldon|url=http://www.professionaljeweler.com/archives/articles/2000/sep00/0900gg1.html|title=A Horse Tale|work=Gems & Gemology|date=September 2000|access-date=2007-09-20|archive-date=2020-07-29|archive-url=https://web.archive.org/web/20200729041316/http://professionaljeweler.com/archives/articles/2000/sep00/0900gg1.html|url-status=dead}}</ref><ref>{{cite web|url=http://www.gia.edu/gems-gemology/winter-1999-inclusions-demantoid-garnet-russia-krzemnicki|doi=10.5741/GEMS_35_4_192|publisher=Gemological Institute of America|title=Diopside Needles as Inclusions in Demantoid Garnet from Russia: A Raman Microspectrometric Study|year=1999|volume=35|issue=4|first=Michael S. |last=Krzemnicki|journal=Gems & Gemology}}</ref>  which is a type of [[asbestos]]. These fibers radiate out from a very small crystal of chromite.<ref name="gia.edu">{{cite web|url=http://www.gia.edu/gems-gemology/summer-1996-green-andradite-garnet-phillips|doi=10.5741/GEMS_32_2_100|title=Russian Demantoid, Czar of the Garnet Family|publisher=Gemological Institute of America|year=1996|volume=32|issue=2|first1=Wm. Revell |last1=Phillips |first2=Anatoly S. |last2=Talantsev|journal=Gems & Gemology}}</ref> These inclusions are feathery golden threads that tend to curve and resemble the tail of a horse, and are therefore referred to as horsetail inclusions.  In [[gemology]], the presence of such inclusions is regarded as 'diagnostic' for natural demantoid (i.e. these inclusions are not found in any other green gemstone).<ref name="gia.edu"/> Some gemstones are more valuable for their inclusions,<ref>{{cite web|url=http://www.gia.edu/howtobuyagemstone/05_Inclusions_Value.swf|title=Inclusions & Value|publisher=Gemological Institute of America|access-date=2012-01-28|archive-url=https://web.archive.org/web/20130211210938/http://www.gia.edu/howtobuyagemstone/05_Inclusions_Value.swf|archive-date=2013-02-11|url-status=dead}}</ref> and 'horsetails' can be regarded as desirable features in demantoid, as they are taken as an indication of prestigious Russian origin,<ref name="HorseTail"/><ref>{{cite web|url=http://www.modernjeweler.com/online/article.jsp?siteSection=1&id=345&pageNum=2|title=Demantoid Garnet|work=Modern Jeweler|date=January 12, 2011|access-date=November 27, 2011|archive-url=https://web.archive.org/web/20111101133805/http://modernjeweler.com/online/article.jsp?siteSection=1&id=345&pageNum=2|archive-date=November 1, 2011|url-status=dead|df=mdy-all}}</ref> although some demantoids from certain other locations (such as Italy and Iran) may also contain 'horsetails', which are regarded as being characteristic of a serpentinite geographic origin,<ref>{{cite web|url=http://www.gia.edu/UK-EN/gems-gemology/winter-2009-demantoid-italy-adamo|doi=10.5741/GEMS_45_4_280|title=Demantoid from Val Malenco, Italy: Review and Update|author=Ilaria Adamo|display-authors=etal|year=2009|volume=45|issue=4|journal=Gems & Gemology}}</ref> and, on the other hand, not all Russian demantoids actually contain 'horsetails'.<ref>{{cite web|url=http://www.gia.edu/gia-faq-garnet-horsetail-inclusion|title=Does a horsetail inclusion guarantee Russian origin?|publisher=Gemological Institute of America}}</ref>
The microstructure of some demantoids is believed to be affected by the presence of 'horsetails' (the 'horsetail' typically originates towards the centre of the nodule, with the fibres branching out and radiating towards the surface), whereas horsetail-free demantoids from other sources frequently display flat crystal faces.<ref>{{cite web|url=http://lgdl.gia.edu/pdfs/f97_GN_demantoid.pdf|title=Gem News|work=Gems & Gemology|date=Fall 1997|pp=222–23|archiveurl=https://web.archive.org/web/20081119154352/http://lgdl.gia.edu/pdfs/f97_GN_demantoid.pdf|archivedate=November 19, 2008|url-status=dead}}</ref>