Samuelsonite

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.

Samuelsonite
General
CategoryPhosphate minerals
Formula
(repeating unit)
(Ca,Ba)Ca8Fe22+Mn22+Al2[(OH)2(PO4)10]
IMA symbolSms[1]
Strunz classification8.BF.10
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupC2/m
Unit cella= 18.495 Å, b= 6.805 Å
c= 14.000 Å, β= 112.75°; Z = 2
Identification
ColorPale yellow
Crystal habitPrismatic crystals, elongated and striated
CleavageFair on {001}
Mohs scale hardness5
LusterAdamantine, Sub-Adamantine
StreakWhite
DiaphaneityTransparent
Specific gravity3.353
Optical propertiesBiaxial (+)
Refractive indexnα = 1.645 - 1.648 nβ = 1.650 - 1.655 nγ = 1.655 - 1.667
Birefringence0.0100-0.0190
References[2][3][4]

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. "General Samuelsonite Information". Retrieved 2 October 2010.
  3. 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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