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Todorokite

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Formula:
(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
System:
Monoclinic
Colour:
Purplish gray, brown to ...
Lustre:
Sub-Vitreous, Resinous, Greasy, Sub-Metallic
Hardness:
Name:
Named in 1934 by Toyofumi Yoshimura after its discovery locality, the Todoroki Mine, Hokkaido, Japan.
A relatively common Mn oxide that occurs in a variety of aggregate forms. Usually fibrous, either compact or isolated. Micaceous aggregates may be confused with ranciéite, fibrous forms with pyrolusite. Compare woodruffite.

As birnessite, it may be a product of mineralization of fungal (e.g., Penicillium spp., Mucor spp., Rhizopus spp.) hyphae; as such is found in cave deposits and waters (vide Burford et al., 2003).


Classification of Todorokite

Approved, 'Grandfathered' (first described prior to 1959)
4.DK.10

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
K : With large (+- medium-sized) cations; tunnel structures
7.8.1.1

7 : MULTIPLE OXIDES
8 : AB3X7
7.4.19

7 : Oxides and Hydroxides
4 : Oxides of Be, Mg and the alkaline earths

Physical Properties of Todorokite

Sub-Vitreous, Resinous, Greasy, Sub-Metallic
Diaphaneity (Transparency):
Opaque
Colour:
Purplish gray, brown to black; brown in transmitted light
Streak:
Brown
Hardness (Mohs):
Tenacity:
Brittle
Cleavage:
Perfect
{100} and {010} perfect.
Fracture:
Splintery
Density:
3.67 g/cm3 (Measured)    3.65 g/cm3 (Calculated)

Optical Data of Todorokite

Type:
Biaxial (-)
RI values:
nα = 2.310 nβ = 2.350
Max Birefringence:
δ = 2.310
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Very High
Optical Extinction:
Y=b, Z>X
Pleochroism:
Visible
Comments:
Pleochroic in brown.

Chemical Properties of Todorokite

IMA Formula:
(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Mindat.org Formula:
(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O

Also given as (Ca,K,Na,Mg,Ba,Mn)(Mn,Mg,Al)6O12.3H2O.
Elements listed in formula:
Common Impurities:
Ba,K,Na

Crystallography of Todorokite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P2/m
Cell Parameters:
a = 9.75 Å, b = 2.84 Å, c = 9.59 Å
β = 90°
Ratio:
a:b:c = 3.433 : 1 : 3.377
Unit Cell Volume:
V 265.55 ų (Calculated from Unit Cell)
Z:
1
Morphology:
Spongy banded and/or reniform aggregates composed of minute lathlike to fibrous crystals. Crystals flattened {010} and elongated [001] with terminal edges inclined about 60° and 70° to [001].
Twinning:
Contact twins with c ^ ć about 60°.
Comment:
β may be variable; formerly given as orthorhombic or tetragonal
X-Ray Powder Diffraction Data:
d-spacingIntensity
9.65 (100)
7.02 (40)
4.82 (70)
4.48 (70)
3.20 (10)
3.07 (40)
2.75 (10)
2.46 (40)
2.42 (10)
2.35 (40)
2.28 (10)
2.20 (5)
2.13 (10)
1.98 (10)
1.91 (5)
1.77 (10)
1.67 (10)
1.64 (10)
1.54 (10)
1.42 (5)
1.406 (5)
Comments:
JCPDS 18-1411 (Charco Redondo, Cuba). See also ICDD 19-83 and ICDD 21-553.

Occurrences of Todorokite

Type Occurrence of Todorokite

Relationship of Todorokite to other Species

4.DK.05Akaganeite(Fe3+,Ni2+)8(OH,O)16Cl1.25 · nH2O
4.DK.05aCoronaditePb(Mn64+Mn23+)O16
4.DK.05aCryptomelaneK(Mn74+Mn3+)O16
4.DK.05aHollanditeBa(Mn64+Mn23+)O16
4.DK.05aManjiroiteNa(Mn74+Mn3+)O16
4.DK.05bMannarditeBa(Ti64+V23+)O16
4.DK.05bPrideriteK(Ti74+Fe3+)O16
4.DK.05bRedledgeiteBa(Ti64+Cr23+)O16
4.DK.05bHenrymeyeriteBa(Ti74+Fe2+)O16
4.DK.05aStrontiomelaneSr(Mn64+Mn23+)O16
4.DK.10Romanèchite(Ba,H2O)2(Mn4+,Mn3+)5O10
7.4.1BromelliteBeO
7.4.2BehoiteBe(OH)2
7.4.3ClinobehoiteBe(OH)2
7.4.4ChrysoberylBeAl2O4
7.4.5Magnesiotaaffeite-2N’2SMg3BeAl8O16
7.4.6Magnesiotaaffeite-6N’3SMg2BeAl6O12
7.4.7PericlaseMgO
7.4.8BruciteMg(OH)2
7.4.9SpinelMgAl2O4
7.4.10MeixneriteMg6Al2(OH)18 · 4H2O
7.4.11LimeCaO
7.4.12PortlanditeCa(OH)2
7.4.13ChlormayeniteCa12Al14O32[◻4Cl2]
7.4.14HydrocalumiteCa4Al2(OH)12(Cl,CO3,OH)2 · 4H2O
7.4.15MarokiteCaMn23+O4
7.4.16Ranciéite(Ca,Mn2+)0.2(Mn4+,Mn3+)O2 · 0.6H2O
7.4.17HollanditeBa(Mn64+Mn23+)O16
7.4.18Romanèchite(Ba,H2O)2(Mn4+,Mn3+)5O10

Other Names for Todorokite

Name in Other Languages:
German:Todorokit
Italian:Todorokite
Japanese:轟石
Simplified Chinese:钙锰矿
钡镁锰矿
Spanish:Todorokita
Traditional Chinese:鈣錳礦
鋇鎂錳礦

Other Information

Not fluorescent in ultraviolet
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Todorokite

Reference List:
Journal of the Faculty of Science, Hokkaido University (1934), series 4, 2, 289-297.

American Mineralogist (1935): 20: 678.

Levinson, A.A. (1960): Second occurrence of todorokite. American Mineralogist, 45, 802-807.

Frondel, C., Marvin, U.B., Ito, J. (1960): New occurrences of todorokite. American Mineralogist, 45, 1167-1173.

American Mineralogist (1979): 64: 1333-1334.

Burns, R.G., Burns, V.M., Stockman, H. (1983): A review of the todorokite-buserite problem: Implications to the mineralogy of marine manganese nodules: American Mineralogist, 68, 972-980.

Golden, D.C., Chen, C.C., Dixon, J.B. (1987): Transformation of birnessite to buserite, todorokite, and manganite under mild hydrothermal treatment. Clays and Clay Minerals, 35, 271-280.

Post, J.E. and Bish, D.L. (1988): Rietveld refinement of the todorokite structure. American Mineralogist 73, 861-869.

Post, J. E., Heaney, P. J., Hanson, J. (2003): Synchroton X-ray diffraction study of the structure and dehydratation behavior of todorokite. American Mineralogist 88, 142-150.

Burford, E.P., Kierans, M., Gadd, G.M. (2003): Geomycology: fungi in mineral substrata. Mycologist: 17(3): 98-107; DOI: 10.1017/S0269915X03003112

Internet Links for Todorokite

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https://www.mindat.org/min-3988.html
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Specimens:
The following Todorokite specimens are currently listed for sale on minfind.com.

Localities for Todorokite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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