Kanoite

Kanoite is a light pinkish brown silicate mineral that is found in metamorphic rocks. It is an inosilicate and has a chemical formula of (Mg,Mn²⁺)₂Si₂O₆.^[2] It is a member of pyroxene group and clinopyroxene subgroup.^[5]

Kanoite
Kanoite exhibited at the Mining Museum of Akita University, Japan
General
Category	Silicate mineral (pyroxene, inosilicate)
Formula (repeating unit)	(Mg,Mn2+)2Si2O6
IMA symbol	Knt[1]
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/c
Unit cell	a = 9.73, b = 8.93 c = 5.26 [Å]; β = 108.56°; Z = 4
Identification
Formula mass	246.73 g/mol
Color	Light pinkish brown
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	[2][3][4]

Crystallography

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.^[3] 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

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.^[2]

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.^[3]

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. Handbook of Mineralogy
3. Classification of Kanoite. In Kanoite, Ralph, J., & Chau, I., Mindat.org
4. Webmineral data
5. Physical Properties of Kanoite. In Kanoite Mineral Data. Barthelmy, D. (1997-2010).

• 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.