Kanoite

from Wikipedia, the free encyclopedia
Kanoite
General and classification
chemical formula Mn 2+ MgSi 2 O 6
Mineral class
(and possibly department) 		Silicates and Germanates
System no. to Strunz
and to Dana 		09.DA.10 ( 8th edition : VIII / F.01)
65.01.01.03
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group P 2 1 / c (No. 14)Template: room group / 14
Lattice parameters a  = 9.739  Å ; b  = 8.939 Å; c  = 5.260 Å
β  = 108.56 °
Formula units Z  = 4
Twinning polysomatic according to {100}
Physical Properties
Mohs hardness 6th
Density (g / cm 3 ) 3.66
Cleavage perfect after {110}
colour light pink brown
Line color White
transparency translucent to transparent
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.715 to 1.728
Birefringence δ = 0.013
Optical character biaxial positive

Kanoite is a very rarely occurring mineral from the mineral class of " silicates and germanates ". It crystallizes in the monoclinic crystal system with the chemical composition (Mn 2+ 1 − x , Mg x ) MgSi 2 O 6 , with 0.5> x ≥ 0.

The crystals, which are usually only a few millimeters in size, are prismatic or irregularly grained. Kanoite is light pink brown transparent to translucent and has a glass luster. The density is 3.66 g / cm 3 , the Mohs hardness is 6.

Etymology and history

Kanoite was discovered in manganese-rich layers of hornblendefacial sediments and basic volcanic rocks on the Oshima Peninsula , Hokkaidō , Japan . Kanoite is found there together with manganese-rich cummingtonite , spessartine and relics of pyrox mangite , which were replaced by kanoite in the course of the metamorphosis.

Kanoit was described by Hideo Kobayashi in 1977. He named the new mineral after Akita University professor of petrology, Dr. Hiroshi Kano, in recognition of his work on the metamorphic rocks of Japan.

classification

In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the Kanoite belonged to the department of " Chain and Band Silicates (Inosilicates) ", where together with Aegirin , Augit , Diopside , Esseneit , Jadeite , Jervisit , Johannsenit , Hedenbergit , clino , Klinoferrosilit , Kosmochlor , Namansilit , Natalyit , omphacite , Petedunnit , pigeonite and spodumene the subgroup of "clinopyroxene" with the system no. VIII / F.01 within the pyroxene group .

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also classifies the Kanoite in the category of "chain and band silicates (inosilicates)". However, this is further subdivided according to the crystal structure, so that the mineral is classified in the sub-section “Chain and band silicates with 2-periodic single chains Si 2 O 6 ; Pyroxene family "is to be found, where together with clinoenstatite, clinoferrosilite, halagurite and pigeonite the group of" Mg, Fe, Mn-clinopyroxene, clinoenstatite group "with the system no. 9.DA.10 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking area , also classifies the Kanoite in the “chain silicate minerals” department. Here it is together with Klinoenstatit, Klinoferrosilit and Pigeonit in the group of " P 2 / c Klinopyroxene" with the system no. 65.01.01 can be found in the subsection " Chain Silicates: Simple unbranched chains, W = 1 with chains P = 2 ".

Modifications and varieties

The compound MnMgSi 2 O 6 is polymorphic and Kanoite is the monoclinic low-temperature modification. Another well-known modification is the orthorhombic orthopyroxen donpeacorite .

Education and Locations

Kanoite is mainly formed during the metamorphosis of manganese-rich calcareous sediments under conditions of the granulite facies . In such rocks Kanoite occurs together with manganese-rich cummingtonite , spessartine and pyrox mangite .

The type locality is the coast near Tatehira on the Oshima Peninsula , Hokkaidō , Japan . Other sites are the Shimozuru Mine in Kyūshū , Japan, the Semail Ophiolite in Bulaydah in the Khawr Fakkan Massif, Oman , the Balmat-Edwards Zinc Region in Balmat in New York , USA and the lead-zinc deposit of Broken Hill in New South Wales , Australia .

Kanoite is also found in some meteorites .

Crystal structure

Crystallographic Data
Crystal system monoclinic
Space group P 2 1 / c (No. 14)Template: room group / 14
Lattice parameters
 a  = 9.739  Å
b  = 8.939 Å
c  = 5.260 Å
β = 108.56 °
Number (Z) of the formula units Z = 4

Kanoite crystallizes monoclinically in the space group P 2 1 / c (space group no. 14) with the structure of clinopyroxene . Template: room group / 14

The distribution of manganese between the two octahedron positions is ordered. Almost all of the Mn is in the more distorted M2 position.

See also

Individual evidence

  1. ↑ a b c d e f g h i j k l m Kobayashi 1977
  2. ↑ Arlt et al. 1998
  3. ↑ T. Arlt, M. Kunz, J. Stolz, T. Armbruster; RJ Angel: PTX data on P2 1 / c-clinopyroxenes and their displacive phase transitions. In: Contributions to Mineralogy and Petrology 2000, 138, pp. 35-45. doi : 10.1007 / PL00007660 .
  4. ↑ Kanoit at mindat.org
  5. ^ Rubin 1997
  6. ↑ Gordon et al. 1981

literature

  • H. Kobayashi: Kanoite, (Mn 2+ , Mg) 2 [Si 2 O 6 ], a new clinopyroxene in the metamorphic rock from Tatehira, Oshima Peninsula, Hokkaido, Japan In: Journal of the Geological Society of Japan 1977, 93, Pp. 537-542 ( PDF (668 kB) ).
  • WA Gordon, DR Peacor, PE Brown, EJ Essene: Exsolution relationships in a clinopyroxene of average composition Ca 0.43 Mn 0.69 Mg 0.82 Si 2 O 6 : X-ray diffraction and analytical electron microscopy. In: American Mineralogist 1981, 66, pp. 127–141 ( PDF (1.6 MB) ).
  • JW Anthony, RA Bideaux, KW Bladh, MC Nichols: Handbook of Mineralogy: Kanoite. American Mineralogical Society, 2001 ( PDF (72 kB) ).
  • AE Rubin: Mineralogy of meteorite groups: An Update. In: Meteoritic & Planetary Science 1997, 32, pp. 733-734 ( bibcode : 1997M & PS ... 32..733R ).
  • T. Arlt, RJ Angel, R. Miletich, T. Armbruster, T. Peters: High-pressure P2 1 / c-C2 / c phase transitions in clinopyroxenes: Influence of cation size and electronic structure. In: American Mineralogist 1998, 83, pp. 1176–1181 ( PDF (785 kB) )
  • T. Arlt, M. Kunz, J. Stolz, T. Armbruster; RJ Angel: PTX data on P2 1 / c-clinopyroxenes and their displacive phase transitions. In: Contributions to Mineralogy and Petrology 2000, 138, pp. 35-45. doi : 10.1007 / PL00007660 .

Web links