Kanoite

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Kanoite
General
Category Silicate mineral
Formula
(repeating unit)
(Mg,Mn2+)2Si2O6
Crystal symmetry Monoclinic 2/m
Unit cell a = 9.73 Å, b = 8.93 Å, c = 5.26 Å; β = 108.56°; Z = 4
Identification
Formula mass 246.73 g
Color Light pinkish brown
Crystal system Monoclinic prismatic
Twinning Polysynthetic
Cleavage Perfect on {110}, {110} - {110} = 88°
Mohs scale hardness 6
Luster vitreous
Diaphaneity Semitransparent
Specific gravity 3.66
Optical properties Biaxial (+)
Refractive index nα = 1.715 nβ = 1.715 nγ = 1.728
Birefringence 0.0130
2V angle 40-42 measured
References [1][2][3]

Kanoite is a light pinkish brown silicate mineral that is found in metamorphic rocks. It is an inosilicate and has a formula of (Mg,Mn2+)2Si2O6.[1] It is a member of pyroxene group and clinopyroxene subgroup.[4]

Crystallography[edit]

Kanoite crystallizes in the monoclinic crystal system. Its Hermann–Mauguin Symbol is 2/m. Under this crystal system, the three axes of the crystal are all different in length. The a and the b axes are perpendicular, and b and c axes are perpendicular. The a and c axes make an oblique shape. The axial ratio for kanoite is a:b:c =1.0894:1:0.5884 and the cell dimensions are: a = 9.73, b = 8.93 and c = 5.26 Å with Z = 4.[2] Kanoite has a 2-fold axis and a mirror plane.

Kanoite is birefringent. It occurs as a mineral has 3 different indices of refraction. When the light passes through the Kanoite medium, the light splits due to unequal reflection from the crystal faces. As kanoite is birefringent, it is also anisotropic. In an anisotropic mineral, the velocity of light differs as the direction of the crystal changes.

Discovery and occurrence[edit]

Kanoite is a rare mineral which was found in Tatehira mine, Kumaishi, Oshima Peninsula, Hokkaido, Japan in 1977. In the type locality kanoite occurs along a joint that cuts a pyroxmangite-cummingtonite metamorphic rock in a manganese ore deposit. The region has undergone contact metamorphism as magma intruded the area. It was named to honor Hiroshi Kano, a petrology professor at Akita University in Japan.[1]

It has also been reported from Broken Hill, New South Wales, Australia, the Semail Ophiolite in Oman, and the Balmat-Edwards Zinc District, Saint Lawrence County, New York.[2]

References[edit]

  • Gnos, E., Armbruster, T., and Nyfeler, D. (1996) Kanoite, donpeacorite and tirodite: Mn-Mg-silicates from a manganiferous quartzite in the United Arab Emirates. European Journal of Mineralogy, 8, 251-261.
  • Kobayashi, H. (1977) Kanoite, (Mn2+;Mg)2[Si2O6], a new clinopyroxene in the metamorphic rock from Tatehira, Oshima Peninsula, Hokkaido, Japan. The Journal of the Geological Society of Japan, 83, 537-542.
  • Arlt, T. and Armbruster, T. (1997) The temperature dependent P21/c-C2/c phase transition in the clinopyroxene kanoite MnMg[Si2O6]: a single-crystal X-ray and optical study. European Journal of Mineralogy, 9, 953–964.
  • Akimoto, S. and Syono, Y. (1972) High pressure transformations in MnSiO3. American Mineralogist, 57, 76–84.
  • Mineral Data Publishing, 2001, “Kanoite.” http://rruff.geo.arizona.edu/doclib/hom/kanoite.pdf. Accessed 21 October 2010.
  • Ralph, Jolyon and Chau, Ida, 5 November 2010, “Kanoite.” http://www.mindat.org/min-2154.html. Accessed 1 November 2010.
  • Barthelmy, David, 1997-2010, “Kanoite Mineral Data.” http://www.webmineral.com/data/Kanoite.shtml. Accessed 7 November 2010.
  • Weisstein, Eric, 1996-2007, “Birefringence.” http://scienceworld.wolfram.com/physics/Birefringence.html. Accessed 7 November 2010.