Editing Andalusite (section)

==Varieties==<!-- Viridite and Kanonaite redirect here-->
The variety [[chiastolite]] commonly contains dark inclusions of carbon or clay which form a [[cruciform]] pattern when shown in cross-section. This stone was known at least from the sixteenth century, being taken to many European countries, as a souvenir, by pilgrims returning from Santiago de Compostela.<ref>{{Cite journal|last=Calvo|first=Miguel|date=2016|title=El "lapis crucifer", "piedra de cruz de Compostela": un elemento importante de los patrimonios geológico y cultural del NW de España|journal=De Re Metallica|volume=6|pages=67–79}}</ref>

'''Viridine''' is a [[green]] variety of andalusite in which [[manganese]] 3+ substitutes for aluminium, the same change is also responsible for the colour.<ref>{{cite journal |last1=Abs-Wurmbach |first1=I. |last2=Langer |first2=K. |last3=Seifert |first3=F. |last4=Tillmanns |first4=Ε. |title=The crystal chemistry of (Mn 3+ , Fe 3+ )-substituted andalusites (viridines and kanonaite), (Al 1-x-y Mn x 3+ Fe 3+ y ) 2 (O{{!}}SiO 4 ): crystal structure refinements, Mössbauer, and polarized optical absorption spectra |journal=Zeitschrift für Kristallographie - Crystalline Materials |date=1 October 1981 |volume=155 |issue=1–4 |pages=81–114 |doi=10.1524/zkri.1981.155.14.81|s2cid=201671728 }}</ref><ref>{{Cite web |title=Minerals Colored by Metal Ions |url=http://minerals.gps.caltech.edu/color_causes/Metal_Ion/index.html |access-date=2023-03-01 |website=minerals.gps.caltech.edu}}</ref> '''Kanonaite''' is a greenish-black mineral related to andalusite and having the approximate composition {{chem2|(Mn0.76Al0.23Fe0.02)AlSiO5}}.<ref>{{cite journal |last1=Vrána |first1=S. |last2=Rieder |first2=M. |last3=Podlaha |first3=J. |title=Kanonaite, (Mn 0.76 3+ Al0.23Fe 0.02 3+ )[6]Al[5][O{{!}}SiO4], a new mineral isotypic with andalusite |journal=Contributions to Mineralogy and Petrology |date=1978 |volume=66 |issue=3 |pages=325–332 |doi=10.1007/BF00373417|s2cid=95925117 }}</ref>

A clear variety found in Brazil and Sri-Lanka can be cut into a gemstone.<ref>{{Cite web |url=http://www.gemstone.org/gem-by-gem/english/andalusite.html |title=''International Colored Gem Association: Anadalusite'' |access-date=2006-07-13 |archive-url=https://web.archive.org/web/20060717224731/http://www.gemstone.org/gem-by-gem/english/andalusite.html |archive-date=2006-07-17 |url-status = dead}}</ref> Faceted andalusite stones give a play of red, green, and yellow colors that resembles a muted form of [[iridescence]], although the colors are actually the result of unusually strong [[pleochroism]].<ref name="FernandesChoudhary2009">{{cite journal |last1=Fernandes |first1=Shyamala |last2=Choudhary |first2=Gagan |title=Gem-quality andalusite from Brazil |journal=Gems & Gemology |date=Summer 2009 |volume=45 |issue=2 |pages=120–129 |doi=10.5741/GEMS.45.2.120 |url=https://www.gia.edu/doc/Summer-2009-Gems-Gemology-Gem-Quality-Andalusite-from-Brazil.pdf |access-date=30 October 2021}}</ref>