Samuelsonite

(repeating unit)(Ca,Ba)Ca8Fe22+Mn22+Al2[(OH)2(PO4)10]IMA symbolSms[1]Strunz classification8.BF.10Crystal systemMonoclinicCrystal classPrismatic (2/m)
(same H-M symbol)Space groupC2/mUnit cella= 18.495 Å, b= 6.805 Å
c= 14.000 Å, β= 112.75°; Z = 2IdentificationColorPale yellowCrystal habitPrismatic crystals, elongated and striatedCleavageFair on {001}Mohs scale hardness5LusterAdamantine, Sub-AdamantineStreakWhiteDiaphaneityTransparentSpecific gravity3.353Optical propertiesBiaxial (+)Refractive indexnα = 1.645 - 1.648 nβ = 1.650 - 1.655 nγ = 1.655 - 1.667Birefringence0.0100-0.0190References[2][3][4]

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,[2] a prospector from Rumney, New Hampshire.

The mineral has a pale yellow color and has a hardness of 5 on Mohs scale.[3] The crystal is generally yellow, flat, and with straited crystals and blue trolleites.[5] 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°.[6] 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

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b "General Samuelsonite Information". Retrieved 2 October 2010.
  3. ^ a b Jolyon Ralph and Ida Chau. "Samuelsonite". mindat.org. Retrieved 2 October 2010.
  4. ^ Handbook of Mineralogy
  5. ^ "Samuelsonite R080081". Retrieved 2 October 2010.
  6. ^ 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.


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