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Kotoite

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Băiţa Mining District (Baita Bihor; Rézbánya), Nucet, Bihor Co., Romania
© Thomas Witzke

Show Kotoite Photos (2)
Formula:
Mg
 
3
[BO
 
3
]
 
2
System:OrthorhombicColour:Colourless; colourless ...
Lustre:VitreousHardness:6½
Name:After Bundjirô Kotô (1856-1935), Japanese geologist and petrographer.
This page provides mineralogical data about Kotoite.

Classification of Kotoite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:5/G.01-10
Nickel-Strunz 10th (pending) edition ID:6.AA.35

6 : BORATES
A : Monoborates
A : BO3, without additional anions; 1(D).
Dana 8th edition ID:24.3.2.1

24 : ANHYDROUS BORATES
3 : AmBn[XO3]p
Hey's CIM Ref.:9.2.3

9 : Borates
2 : Borates of Be and Mg
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Type Occurrence of Kotoite

Type Locality:North orebody (New orebody), Hol Kol Mine (Holgol; Suan; Namjong), Suan-gun, North Hwanghae Province, North Korea
Year of Discovery:1939
Geological Setting of type material:Contact zone of granitic intrusion into dolomite.
Associated Minerals at type locality:
SzaibélyiteSpinelLudwigiteForsteriteFluoborite
Clinohumite

Physical Properties of Kotoite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent
Colour:Colourless; colourless in transmitted light
Hardness (Mohs):6½
Cleavage:Perfect
On {110}
Parting:On {101}. Also exhibits translation gliding.
Density (measured):3.1 g/cm3
Density (calculated):3.06 g/cm3

Crystallography of Kotoite

Crystal System:Orthorhombic
Cell Parameters:a = 5.4Å, b = 8.42Å, c = 4.5Å
Ratio:a:b:c = 0.641 : 1 : 0.534
Unit Cell Volume:V 204.61 ų (Calculated from Unit Cell)
Morphology:Massive, granular.
Twinning:On {101} as the twin and composition plane, polysynthetic.

Optical Data of Kotoite

Type:Biaxial (+)
RI values: nα = 1.652 nβ = 1.653 nγ = 1.673
2V:Measured: 21° , Calculated: 26°
Maximum Birefringence:δ = 0.021

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate
Dispersion:relatively weak

Chemical Properties of Kotoite

Formula:
Mg
 
3
[BO
 
3
]
 
2
Essential elements:B, Mg, O
All elements listed in formula:B, Mg, O

Relationship of Kotoite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
6.AA.05Sassolite
H
 
3
BO
 
3
6.AA.15Nordenskiöldine
CaSn
4+
 
[BO
 
3
]
 
2
6.AA.15Tusionite
Mn
2+
 
Sn
4+
 
[BO
 
3
]
 
2
6.AA.35Jimboite
(Mn
2+
 
,Mg)
 
3
[BO
 
3
]
 
2
6.AA.40Takedaite
Ca
 
3
[BO
 
3
]
 
2
Related Minerals - Hey's Index Grouping:

- +
9.2.1Hambergite
Be
 
2
[O|OH|BO
 
2
]
9.2.2Suanite
Mg
 
2
[B
 
2
O
 
5
]
9.2.4Szaibélyite
Mg
 
2
[B
 
2
O
 
5
] · H
 
2
O
9.2.5Preobrazhenskite
Mg
 
3
B
 
11
O
 
15
(OH)
 
9
9.2.6Aksaite
Mg[B
 
6
O
 
7
(OH)
 
6
] · 2H
 
2
O
9.2.7Wightmanite
Mg
 
5
[O|(OH)
 
5
|BO
 
3
] · 2H
 
2
O
9.2.8Pinnoite
Mg[B
 
2
O
 
5
] · 3H
 
2
O
9.2.9Kurnakovite
Mg(H
 
4
B
 
3
O
 
7
)(OH) · 5H
 
2
O
9.2.10Halurgite
Mg
 
2
[B
 
4
O
 
7
]
 
2
 · 5H
 
2
O
9.2.11Inderite
Mg(H
 
4
B
 
3
O
 
7
)(OH) · 5H
 
2
O
9.2.12Hungchaoite
Mg[B
 
4
O
 
7
] · 9H
 
2
O
9.2.13Admontite
Mg[B
 
6
O
 
7
(OH)
 
6
] · 4H
 
2
O
9.2.14Mcallisterite
Mg
 
2
[B
 
6
O
 
7
(OH)
 
6
]
 
2
 · 9H
 
2
O
9.2.15Rivadavite
Na
 
6
Mg[B
 
6
O
 
7
(OH)
 
6
]
 
4
 · 10H
 
2
O
9.2.16Kaliborite
KMg
 
2
H[B
 
6
O
 
8
(OH)
 
5
]
 
2
(H
 
2
O)
 
4
9.2.17Iquiqueite
K
 
3
Na
 
4
Mg(CrO
 
4
)B
 
24
O
 
39
(OH)·12H
 
2
O

Other Names for Kotoite

Other Languages:
German:Kotoit
Russian:Котоит
Spanish:Kotoita

Other Information

Thermal Behaviour:Melting Point = ~ 1340° C.
Other Information:Readily soluble in warm HCl or H2SO4.

Alters to Szaibelyite under hydrothermal conditions.
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Kotoite

Reference List:Mallard (1887) Comptes rendu de l’Académie des sciences de Paris: 105: 1260 (artificial crystals).

Mallard (1887) Annales des mines: 12(8): 427 (artificial crystals).

Mallard (1889) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 15: 650 (artificial crystals).

Watanabe, T. (1939), Kotoit, ein neues gesteinsbildenes magnesiumborat. Mineralogische und petrographische Mitteilungen, Vienna: 50: 441-463.

Watanabe, T. (1939) Mineralogische und petrographische Mitteilungen, Vienna: 51: 162.

Watanabe, T. (1939) Fortschritte der Mineral: 23: clxvi.

American Mineralogist (1939): 24: 406.

Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged: 328-329.

Zeitschrift für Kristallographie (1984): 16: 129.

Grew, E.S., and Anovitz, L.M. (1996) BORON: Mineralogy, Petrology and Geochemistry, second edition, as revised (2002).

Articles/Blogs about Kotoite

Internet Links for Kotoite

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    Localities for Kotoite

    Hide Locality List
    The 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.
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    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    China
     
    • Guangdong Province
      • Heyuan Prefecture
        • Lianping Co.
    		Anthony, J.W. et al.: Handbook of Mineralogy
    • Hunan Province
      • Hengyang Prefecture
        • Changning Co.
          • Qiliping
    		Anthony, J.W. et al.: Handbook of Mineralogy
    Japan
     
    • Honshu Island
      • Tohoku Region
        • Iwate Prefecture
          • Miyako City
            • Neichi mine
    		Masutomi Museum specimens (Kyoto)
    North Korea
     
    • North Hwanghae Province
      • Suan-gun
    		Tschermaks Min.Petr.Mitt.(1939) 50, 441-463; Dana 7:II::323,370,376.
    Watanabe, T. : Boron mineral resources in Korea (in: Geology and Mineral Resources of the Far East, University of Tokyo Press, 1969)
    Tschermaks Min. Petr. Mitt. (1939): 50: 441-463; Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 323, 328, 370,376.
    Watanabe, T. : Boron mineral resources in Korea (in: Geology and Mineral Resources of the Far East, University of Tokyo Press, 1969)
    Romania
     
    • Bihor Co.
      • Nucet
    		Ş. Marincea: "Suanite in two boron-bearing magnesian skarns from Romania: data on a longtime ignored mineral species", Neues Jahrbuch für Mineralogie - Abhandlungen 182:183-192 (2006)
    Ş. Marincea: "Suanite in two boron-bearing magnesian skarns from Romania: data on a longtime ignored mineral species", Neues Jahrbuch für Mineralogie - Abhandlungen 182:183-192 (2006)
    Russia
     
    • Eastern-Siberian Region
      • Saha Republic (Sakha Republic; Yakutia)
    		[World of Stones 12:49]
        • Polar Yakutia
          • Dogdo River Basin
            • Tas-Khayakhtakh Range
    		Pavel M. Kartashov data
    Rudnev, V.V., Chukanov, N.V., Nechelyustov, G.N., Yamnova, N.A. (2007): Hydroxylborite, Mg3(BO3)(OH)3, a new mineral, and the isomorphous fluoborite-hydroxylborite series. Proceedings of the Russian Mineralogical Society, 136(1), 69-82.; http://maurice.strahlen.org/yakutia/yakutia.htm
        • Verkhoyansk
          • Yana River Basin
            • Dogdo river
    		W. Schreyer et al. (2003) Eur. Journ. Mineral. 15, 1007-1018
    USA
     
    • Washington
      • Snohomish Co.
        • Darrington
          • Jumbo Mountain
    		Minerals of Washington, Bart Cannon, 1975
    Mineral and/or Locality
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