{{Infobox mineral | name = Samuelsonite | category = Phosphate minerals | boxwidth = | boxbgcolor = | image = Samuelsonite.png | imagesize = | caption = | formula = (Ca,Ba)Ca<sub>8</sub>Fe<sub>2</sub><sup>2+</sup>Mn<sub>2</sub><sup>2+</sup>Al<sub>2</sub>[(OH)<sub>2</sub>(PO<sub>4</sub>)<sub>10</sub>] | IMAsymbol = Sms<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 = 8.BF.10 | system = Monoclinic | class = Prismatic (2/m) <br/><small>(same H-M symbol)</small> | symmetry = ''C2/m'' | unit cell = a= 18.495&nbsp;Å, b= 6.805&nbsp;Å <br/>c= 14.000&nbsp;Å, β= 112.75°; Z&nbsp;=&nbsp;2 | color = Pale yellow | habit = Prismatic crystals, elongated and striated | cleavage = Fair on {001} | fracture = | tenacity = | mohs = 5 | luster = Adamantine, Sub-Adamantine | refractive = nα = 1.645 - 1.648 nβ = 1.650 - 1.655 nγ = 1.655 - 1.667 | opticalprop = Biaxial (+) | birefringence = 0.0100-0.0190 | pleochroism = | streak = White | gravity = 3.353 | density = | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Transparent | other = | references = <ref name="smd"/><ref name="mindat"/><ref name=HBM>[https://rruff.geo.arizona.edu/doclib/hom/samuelsonite.pdf Handbook of Mineralogy]</ref> }}

'''Samuelsonite''' is a complex mineral that is found near North Groton, Grafton County, New Hampshire, US. Additionally, it is most commonly found as a secondary mineral in granite pegmatite. Samuelsonite is named after Peter B. Samuelson,<ref name="smd">{{cite web|title=General Samuelsonite Information|url=https://webmineral.com/data/Samuelsonite.shtml|accessdate=2 October 2010}}</ref> a prospector from Rumney, New Hampshire.

The mineral has a pale yellow color and has a hardness of 5 on Mohs scale.<ref name="mindat">{{cite web|title=Samuelsonite|url=http://www.mindat.org/min-3517.html|publisher=mindat.org|accessdate=2 October 2010|author=Jolyon Ralph and Ida Chau}}</ref> The crystal is generally yellow, flat, and with straited crystals and blue trolleites.<ref>{{cite web|title=Samuelsonite R080081|url=https://rruff.info/samuelsonite/display=default/|accessdate=2 October 2010}}</ref> Samuelsonite is monoclinic. There are three vectors of unequal length in this crystal system. The three vectors form a rectangular prism with a parallelogram at the base. Therefore, two of the vectors are perpendicular, while the third makes an angle that is not equal to 90°.<ref>Rapp Jr. G.R., Campbell, T.J., and Roberts, W.L. (1990) Enclycopedia of Minerals (2nd Edition) 797 p. Library of Congress Cataloging, Washington, D.C.</ref> Samuelsonite has biaxial birefringence (trirefringence), meaning when light passes through the optic axis it is split into two rays due to the difference in refractive index of the ray with parallel polarized light compared to the ray with perpendicular polarized light.

==References== {{reflist}}

Category:Monoclinic minerals Category:Minerals in space group 12 Category:Phosphate minerals

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