thumb|Cross-section of a rock with mariposite [[Image:Mariposite monument Cathey's Valley.jpg|thumb|A monument in Cathey's Valley, a community in Mariposa County, California, utilizing mariposite]] thumb|A close-up of one of the rocks in the monument in Cathey's Valley '''Mariposite''' is a mineral which is a chromium-rich variety of mica, which imparts an attractive green color to the generally white dolomitic marble in which it is commonly found. It was named for Mariposa, California, United States, though it can be found in several other places in the Sierra Nevada. It is also found in Marblemount, Washington, in the North Cascades, as well as in a few locations in Canada (Newfoundland, where it is called ''virginite'', Ontario, and Quebec). Mariposite has also been found outside North America: in France, Austria, Spain, Sweden, China, Japan, Papua New Guinea, and Venezuela.<ref>{{cite web |url=https://www.mindat.org/min-10003.html |title=Mariposite |publisher=Mindat.org |access-date=2026-01-20}}</ref>
It is not recognized as a valid mineral by the International Mineralogical Association, but is a chromium-rich phengite, which is a high-silica variety of muscovite. It is the chromium that gives mariposite its distinctive green color.
The term "mariposite" also refers to the stone in which the green mica is found. This stone is metamorphic rock, containing varying amounts of dolomite and quartz. Larger proportions of quartz give it a more attractive, translucent appearance. It is used as a decorative construction material, in walls, monuments, and bridges. It is also made into jewelry.<ref>[https://geology.com/rocks/mariposite.shtml Mariposite by Hobart M. King, Geology.com]</ref>
== Chemical composition == The chemical formula of mariposite is {{chem2|K(Al,Cr)2(Al,Si)4O10(OH)2}}.<ref>{{Cite web|url=http://www.mindat.org/min-10003.html|title=Mariposite|last=|first=|date=|website=Mindat|archive-url=|access-date=}}</ref>
==References== {{reflist}}
==External links== *[https://www.mindat.org/locentry-846761.html Mariposite from the Alameda Mine by Mindat]
Category:Potassium minerals Category:Aluminium minerals Category:Chromium minerals Category:Mariposa County, California Category:Dioctahedral mica group