lizardite
{{Short description|Magnesium phyllosilicate mineral of the serpentine group}}
{{Infobox mineral
| image = file:Lizardit.jpg
| strunz = 9.ED.15
| dana = 71.01.2b.02
| formula = {{chem2|Mg3(Si2O5)(OH)4}}
| system = Trigonal
| color = Green, red, purple, black, brown, light yellow to white
| mohs = 2.5
| luster = Resinous, waxy, greasy
| streak = White
| gravity = 2.55
}}
Lizardite is a mineral from the serpentine subgroup{{Cite book|last=Allaby|first=Michael|url=https://books.google.com/books?id=zZXHDwAAQBAJ&dq=Lizardite+dictionary&pg=PT1107|title=A Dictionary of Geology and Earth Sciences|date=2020-01-09|publisher=Oxford University Press|isbn=978-0-19-257570-8|language=en}} with formula {{chem2|Mg3(Si2O5)(OH)4}}, and the most common type of mineral in the subgroup.{{Cite web|title=Lizardite gemstone information|url=https://www.gemdat.org/gem-2425.html|access-date=2021-10-26|website=www.gemdat.org}} It is also a member of the kaolinite-serpentine group.{{cite book |last1=Gaines |first1=Richard V. |last2=Skinner |first2=H. Catherine W. |last3=Foord |first3=Eugene E. |last4=Mason |first4=Brian |last5=Rosensweig |first5=Abraham |title=Dana's new mineralogy : the system of mineralogy of James Dwight Dana and Edward Salisbury Dana. |date=1997 |publisher=Wiley |location=New York |isbn=978-0471193104 |edition=8th, entirely rewritten and greatly enl.}}
Lizardite may form a solid-solution series with the nickel-bearing népouite (pure end-member: {{chem2|Ni3(Si2O5)(OH)4}}). Intermediate compositions {{chem2|(Mg,Ni)3(Si2O5)(OH)4}} are possible, with varying proportions of magnesium and nickel.{{cite journal |last1=Brindley |first1=G.W. |last2=Wan |first2=Hsien-Ming |title=Compositions, structures, and thermal behavior of nickel-containing minerals in the lizardite-nepouite series |journal=American Mineralogist |year=1975 |volume=60 |pages=863–871 |url=https://pubs.geoscienceworld.org/msa/ammin/article-abstract/60/9-10/863/543147/Compositions-structures-and-thermal-behavior-of |access-date=3 November 2021}} However, the lizardite end-member is much more common than pure népouite, a relatively rare mineral most often formed by the alteration of ultramafic rocks.
Extremely fine-grained, scaly lizardite (also called orthoantigorite) comprises much of the serpentine present in "serpentine marbles". It is triclinic, has one direction of perfect cleavage, and may be white, yellow or green. Lizardite can be translucent or opaque, and have a soapy feel. It may be pseudomorphous after enstatite, olivine or pyroxene, in which case the name bastite is sometimes applied. Bastite may have a silky lustre.
Name
Lizardite was named by Eric James William Whittaker and Jack Zussman in 1955 after the place it was first reported, the Lizard Peninsula, (from the {{langx|kw|An Lysardh}}) in southern Cornwall, England, United Kingdom.
Scyelite is a synonym of lizardite.{{mindat|name=Lizardite|id=2425}}
Characteristics
= Chemistry =
Antigorite and lizardite commonly coexist metastably;{{Cite book|last1=Alexander|first1=Earl B.|url=https://books.google.com/books?id=NHs8DwAAQBAJ|title=Serpentine Geoecology of Western North America: Geology, Soils, and Vegetation|last2=Coleman|first2=Robert G.|last3=Keeler-Wolfe|first3=Todd|last4=Keeler-Wolfe|first4=Senior Vegetation Ecologist Wildlife and Habitat Data Analysis Branch Todd|last5=Harrison|first5=Susan P.|date=2007-03-22|publisher=Oxford University Press, USA|isbn=978-0-19-516508-1|language=en}}{{Rp|24}} lizardite may also be able to turn into antigorite at over 350 degrees.{{Cite book|url=https://books.google.com/books?id=MvmxAwAAQBAJ&dq=lizardite+discovered&pg=PA712|title=Earth and Life Processes Discovered from Subseafloor Environments: A Decade of Science Achieved by the Integrated Ocean Drilling Program (IODP)|date=2014-12-03|publisher=Elsevier|isbn=978-0-444-62611-0|language=en}}{{Rp|page=712}}
Lizardite contains H2O in excess of the nominal formula, as does chrysotile. It has a high amount of Fe2O3 and a low amount of FeO.{{Cite book|last1=Roberts|first1=B. A.|url=https://books.google.com/books?id=Abb1CAAAQBAJ&dq=Lizardite&pg=PA11|title=The Ecology of Areas with Serpentinized Rocks: A World View|last2=Proctor|first2=J.|date=2012-12-06|publisher=Springer Science & Business Media|isbn=978-94-011-3722-5|language=en}}{{Rp|page=8}}
One study found that lizardite has a high amount of SiO2 and a low amount of Al2O3.{{Cite book|last1=Deer|first1=William Alexander|url=https://books.google.com/books?id=5WEYTb9UAwQC&dq=Lizardite+Canada&pg=PA193|title=Rock Forming Minerals: Layered Silicates Excluding Micas and Clay Minerals, Volume 3B|last2=Howie|first2=Robert Andrew|last3=Zussman|first3=J.|date=2009|publisher=Geological Society of London|isbn=978-1-86239-259-5|language=en}}{{Rp|page=193}}
= Formation =
Lizardite is commonly a result from the hydrothermal metamorphism or retrograde metamorphism of mafic minerals such as olivine, pyroxene or amphibole, in ultrabasic rocks.
Occurrence
= Geological occurrence =
Lizardite is commonly found in ophiolite{{cite journal |last1=Laurora |first1=Angela |last2=Brigatti |first2=Maria Franca |last3=Maiferrari |first3=Daniele |last4=Galli |first4=Ermanno |last5=Rossi |first5=Antonio |last6=Ferrari |first6=Massimo |title=The crystal chemistry of lizardite-1T from northern Apennines ophiolites near Modena, Italy |journal=The Canadian Mineralogist |date=2011 |volume=49 |issue=4 |pages=1045–1054 |doi=10.3749/canmin.49.4.1045 |bibcode=2011CaMin..49.1045L |url=https://rruff-2.geo.arizona.edu/uploads/CM49a_1045.pdf |access-date=3 November 2021}} and is often intergrown with brucite.{{Rp|page=8}} It is also found with magnetite and the other serpentine minerals.{{Cite book|last1=Pichler|first1=Hans|url=https://books.google.com/books?id=5xArBgAAQBAJ&dq=Lizardite&pg=PA119|title=Rock-forming Minerals in Thin Section|last2=Schmitt-Riegraf|first2=Cornelia|date=2012-12-06|publisher=Springer Science & Business Media|isbn=978-94-009-1443-8|language=en}}{{Rp|118–119}}
= Locations found =
== Canada ==
As of 1989, only a single specimen of lizardite had been found in Mont-Saint-Hilaire, Quebec where it may occur in altered pegmatites.{{Cite book|last1=Mandarino|first1=Joseph Anthony|url=https://books.google.com/books?id=u_08AAAAIAAJ&dq=Lizardite+found&pg=PA184|title=Monteregian Treasures: The Minerals of Mont Saint-Hilaire, Quebec|last2=Anderson|first2=Violet|date=1989-03-31|publisher=CUP Archive|isbn=978-0-521-32632-2|language=en}}{{Rp|184}}
== United States ==
Lizardite can be found in the United States.{{Cite web|date=2017-03-14|title=Lizardite|url=https://nationalgemlab.in/lizardite/|access-date=2021-10-27|website=National Gem Lab|language=en-US}} In Pennsylvania It was discovered in the 1960s.{{Cite book|last=Montgomery|first=Arthur|url=https://books.google.com/books?id=YoMbwoEJGP0C&dq=lizardite&pg=PA55|title=Mineralogy of Pennsylvania 1922-1965: Supplementing and Updating Gordon's the Mineralogy of Pennsylvania (1922)|date=2008|publisher=Academy of Natural Sciences|isbn=978-1-4223-1786-0|language=en}}{{Rp|page=55}} With it being the most abundant mineral in Nottingham County Park.{{Cite book|last=Pazzaglia|first=Frank James|url=https://books.google.com/books?id=vQdHRNitfOoC&dq=Lizardite+museum&pg=PA19|title=Excursions in Geology and History: Field Trips in the Middle Atlantic States|date=2006-01-01|publisher=Geological Society of America|isbn=978-0-8137-0008-3|pages=19|language=en}}
In Minnesota it can be found on the north shore of Lake Superior.
In Montana, the Stillwater igneous complex is a prominent location for the mineral.
== United Kingdom ==
Lizardite has a type locality at Lizard Peninsula, Cornwall, in the United Kingdom. It is found in green, red purple, brown and black form and used as both a semi-precious gemstone or for ornamental uses.
Scotland is a notable source of lizardite.{{Cite web|title=Serpentine Value, Price, and Jewelry Information - Gem Society|url=https://www.gemsociety.org/article/serpentine-jewelry-and-gemstone-information/|access-date=2021-10-27|website=International Gem Society|language=en}} Lizardite has been reported in Wales. At Holy Island, Anglesey lizardite has been found to be associated with antigorite.{{Cite web|title=Mineral Database - Mineralogy of Wales|url=https://museum.wales/mineralogy-of-wales/database/?mineral=304&name=Lizardite|access-date=2021-10-26|website=National Museum Wales|language=en}}
== South Africa ==
In the Frank Smith mine located in South Africa, lizardite was the dominant serpentine mineral.{{Rp|page=212}}
Orange lizardite has been found at the Wessels mine.{{Cite journal|last1=Rossman|first1=George|last2=Laurs|first2=Brendan M.|date=2014|title=Orange Lizardite from South Africa|url=https://resolver.caltech.edu/CaltechAUTHORS:20180424-123619251|journal=Journal of Gemmology|language=en|volume=34|issue=2|pages=98–99|issn=1355-4565}}