Editing Agate (section)

=== North America ===
* ''Coldwater agates'', such as the [[Lake Michigan]] cloud agate, are sedimentary agates that formed within [[limestone]] and [[Dolomite (rock)|dolomite]] strata of marine origin. Like volcanic agates, Coldwater agates formed from silica gels that lined pockets and seams within the bedrock. These agates are typically less colorful, with banded lines of grey and white chalcedony.<ref>{{Cite book|last=Garvin|first=Paul|url=https://books.google.com/books?id=3a1XkpBGdAcC&q=Coldwater+agates&pg=PA65|title=Iowa's Minerals: Their Occurrence, Origins, Industries, and Lore|date=2010-09-13|publisher=University of Iowa Press|isbn=978-1-60938-014-4|language=en|access-date=2020-10-29|archive-date=2023-08-26|archive-url=https://web.archive.org/web/20230826164756/https://books.google.com/books?id=3a1XkpBGdAcC&q=Coldwater+agates&pg=PA65|url-status=live}}</ref>
* ''Crazy lace agate'' is a brightly colored lace agate from [[Mexico]] with a complex pattern, demonstrating randomized distribution of contour lines and circular droplets, scattered throughout the rock. The stone is typically colored red and white but is also seen to exhibit yellow and grey combinations as well.<ref>{{Cite book|last1=Atkinson|first1=Bill|url=https://books.google.com/books?id=ZSP94tREw7AC&q=Crazy+lace+agate&pg=PA165|title=Within the Stone: Photography|last2=Ackerman|first2=Diane|date=2004|publisher=BrownTrout Publishers|isbn=978-0-7631-8189-5|language=en|access-date=2020-10-29|archive-date=2023-08-26|archive-url=https://web.archive.org/web/20230826164751/https://books.google.com/books?id=ZSP94tREw7AC&q=Crazy+lace+agate&pg=PA165|url-status=live}}</ref> Crazy lace agate is a vein agate that formed in sedimentary rock of the late [[Cretaceous]] period.<ref name="pabian" />{{rp|p=121}}
* ''Dugway geodes'' are a type of thunder egg found in [[Utah]]. They are typically light grey to blue and often contain hollow cavities lined with drusy quartz.<ref name="pabian" />{{rp|p=92}}
* [[Fairburn Agate|''Fairburn agates'']] are rare fortification agates named for [[Fairburn, South Dakota]]. They are sedimentary agates that originated during the [[Pennsylvanian (geology)|Pennsylvanian]] period, and then weathered from their host rock and redeposited during the [[Oligocene]] epoch in parts of South Dakota and [[Nebraska]].<ref>{{cite web |title=Fairburn Agate |url=https://www.mindat.org/min-1441.html |website=mindat.org |publisher=Hudson Institute of Mineralogy |access-date=16 February 2025}}</ref>
* ''Laguna agate'' is a brightly colored agate variety that was first discovered in Ojo Laguna, Chihuahua, Mexico.<ref>{{Cite web |title=Laguna Agate |url=https://www.mindat.org/min-7611.html |access-date=2025-02-16 |website=www.mindat.org}}</ref> It features vibrant bands in shades of red, orange, pink, or purple. Laguna agates formed in [[andesite]] and are geologically young. They frequently contain inclusions and many exhibit parallax or shadow banding.<ref name="pabian" />{{rp|pp=114–115}}
* ''[[Lake Superior agate]]s'' are believed to be the world's oldest agates;<ref>{{cite web |title=Lake Superior Agate |url=https://www.mindat.org/min-9253.html |website=mindat.org |publisher=Hudson Institute of Mineralogy |access-date=16 February 2025}}</ref> they formed as nodules in basalt up to 1.2 billion years ago during the Late [[Precambrian]]. These agates are primarily found near the shores of [[Lake Superior]] in the [[United States|U.S.]] states of [[Minnesota]], [[Michigan]], and [[Wisconsin]], and in the [[Canada|Canadian]] province of [[Ontario]]. They are not named after the lake, but rather the Lake Superior [[Till]], the [[Pleistocene]] glacial deposit in which they are found.<ref name="pabian" />{{rp|pp=83–84}} This deposit also extends into portions of [[Iowa]], [[Nebraska]], [[Kansas]], and [[Missouri]], and Lake Superior agates have been carried south by the [[Mississippi River]] into [[Arkansas]] and [[Louisiana]]. Lake Superior agates have bands in shades of red, orange, yellow, brown, white, and grey. They can contain a variety of structural features, including eyes, tubes, sagenite, dendrites, faults, and geodes.<ref name="lynch whole book">{{Cite book |last=Lynch |first=Dan R. |title=Lake Superior Agates Field Guide |last2=Lynch |first2=Bob |date=2012 |publisher=Adventure Publications |isbn=978-1-59193-282-6}}</ref>
* ''Lysite agate'' is a vein agate named after Lysite Mountain, [[Wyoming]]. It is frequently colorful and may contain moss and plumes in addition to bands.<ref name="pabian" />{{rp|p=79}}
* ''Nebraska blue agate'' is a sedimentary agate with dendritic patterns that formed during the Oligocene epoch. It can be found throughout northwestern Nebraska and southwestern South Dakota.<ref name="pabian" />{{rp|p=80}}
* Oregon is known for several different varieties of agate. It is probably best known for its ''thunder eggs'', which form in rhyolitic ash and have a brown rhyolite shell that is usually filled with blue and white agate.<ref name="pabian" />{{rp|p=99}} ''Holley blue agate'' (also spelled "Holly blue agate") is a rare lavender to blue agate found only near [[Holley, Oregon]].<ref name="pabian" />{{rp|p=103}}
* ''[[Patuxent River stone]]'' is a red and yellow form of agate only found in [[Maryland]], where it is the state gem.<ref>{{cite web |title=Maryland State Gem - Patuxent River Stone |url=https://msa.maryland.gov/msa/mdmanual/01glance/symbols/html/gem.html |website=maryland.gov |publisher=Maryland State Archives |access-date=16 February 2025}}</ref>
* ''Sweetwater agates'' are small moss agates found in [[Miocene]] age [[sandstone]] near Sweetwater River, Wyoming. They also contain brown or black dendrites and fluoresce under [[Ultraviolet|UV]] light.<ref name="pabian" />{{rp|p=79}}
* ''Turritella agate'' is a brown fossil agate formed from the remains of an extinct species of freshwater snail ([[Elimia tenera]]) with an elongated spiral shell. The name is a misnomer; it was originally thought to be the fossil of a different genus of gastropods, [[Turritella]]. It is found in the [[Green River Formation]] of Wyoming.<ref name="turritella">{{Cite web |last=King |first=Hobart M. |title=Turritella Agate |url=https://geology.com/gemstones/turritella/ |access-date=16 February 2025 |website=geology.com}}</ref>
* Other varieties of agate have also been found in nearly every U.S. state, northern Mexico, and in the Canadian provinces of [[Nova Scotia]], [[Manitoba]], and [[British Columbia]].<ref name="pabian" />{{rp|pp=76–121}}
<gallery mode="packed" heights="130px">
Crazy Lace Agate - Macro Panorama.jpg|Crazy lace agate
Dugway Geode (Juab County, Utah, USA) 2 (34581522545).jpg|Dugway geode from Utah
Fairburn Agate (ultimately derived from the Minnelusa Formation, Pennsylvanian-Permian; collected east of the Black Hills, western South Dakota, USA) 26 (32406082220).jpg|Fairburn agate from western South Dakota
LagunaAgateFromMexico.jpg|Laguna agate
Agate nodule ("Lake Superior Agate") (floor of Lake Superior, offshore Keweenaw Peninsula, Michigan USA) 2 (33741645898).jpg|Rough Lake Superior agate from [[Keweenaw Peninsula]], Michigan
Thunder Egg Agate (Priday Blue Bed, John Day Formation, Miocene; near Madras, Oregon, USA) 3 (33992544563).jpg|Thunder egg from Oregon
Holley Blue Agate (Linn County, Oregon, USA) 9.jpg|Holley blue agate from Oregon
Elimia fossils Wyoming.jpg|alt=An irregular dark stone with a flat polished front; many white fragments of elongated, spiral, "corkscrew" shells seem to float in the dark stone|Turritella agate (''Elimia tenera'')
Chalcedony (Variety Agate)-262773.jpg|Agate from British Columbia
</gallery>