{{Infobox mineral | name = Madocite | category = Sulfosalt mineral | boxwidth = | boxbgcolor = | image = | imagesize = | caption = | formula = {{chem2|Pb17(Sb,As)16S41}} | IMAsymbol = Mdc<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref> | molweight = | strunz = 2.LB.30 | system = Orthorhombic | class = Pyramidal (mm2) <br/><small>(same H-M symbol)</small> | symmetry = ''Pb2a'' | unit cell = a = 27.2 Å, b = 34.1 Å, <br/>c = 8.12 Å; Z = 4 | color = Grayish black | habit = Elongated and striated crystals; massive | twinning = | cleavage = {010} Perfect | fracture = Conchoidal | tenacity = | mohs = 3.25 | luster = Metallic | refractive = | opticalprop = | birefringence = | pleochroism = Strong, from white to gray | streak = Grayish black, shining | gravity = 5.98 | density = | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Opaque | other = | references = <ref>[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Madocite Mineralienatlas]</ref><ref name=Mindat>[http://www.mindat.org/min-2517.html Mindat.org]</ref><ref>(1968) American Mineralogist, 53, 1421</ref><ref name=Webmin>[http://webmineral.com/data/Madocite.shtml Webmineral data]</ref><ref name=HBM>Anthony, J. W., Bideaux, R. A., Bladh, K. W., and Nichols, M. C. (1990) Handbook of Mineralogy: Volume 1: Elements, Sulfides, Sulfosalts. 306 p. http://rruff.geo.arizona.edu/doclib/hom/madocite.pdf {{Webarchive|url=https://web.archive.org/web/20080515200938/http://rruff.geo.arizona.edu/doclib/hom/madocite.pdf |date=2008-05-15 }}</ref> }} '''Madocite''' is a mineral with a chemical formula of {{chem2|Pb17(Sb,As)16S41}}. Madocite was named for the locality of discovery, Madoc, Ontario, Canada. It is found in the marbles of the Precambrian Grenville Limestone.<ref name=HBM/> It is orthorhombic (rectangular prism with a rectangular base) and in the point group ''mm2''. Its crystals are elongated and striated along [001] to a size of 1.5 mm.
Madocite is anisotropic and classified as having high relief. It also displays strong pleochroism.<ref name=Webmin/>
Madocite is found in small clusters in marble pits (near Madoc, Ontario), and was originally categorized in the 1920s as an unidentified sulfosalt mineral in an assemblage of pyrite, sphalerite, and jamesonite in marble. Later research was done by John L. Jambor in the 1960s who went to the site and collected samples of the assemblages.<ref>[http://www.corpusetampois.com/cse-guettardite.html History of discovery]</ref>
==References== {{Reflist}}
Category:Antimony minerals Category:Arsenic minerals Category:Lead minerals Category:Sulfosalt minerals Category:Orthorhombic minerals
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