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Pentahydroborite

Big Photo

Fuka mine, Bitchu-cho (Bicchu-cho), Takahashi, Okayama Prefecture, Chugoku Region, Honshu Island, Japan
© 2008, J .Weissman

Show Pentahydroborite Photos (5)
Formula:
CaB
 
2
O(OH)
 
6
 · 2H
 
2
O
System:TriclinicColour:Colourless
Hardness:2½
Name:The "penta" in pentahydroborite is rather a misnomer for a species with only 2 waters, but this came about because the 6 (OH) had originally been mistaken for 3 extra waters.
This page provides mineralogical data about Pentahydroborite.

Classification of Pentahydroborite

IMA status:Approved
Strunz 8th edition ID:5/H.04-30
Nickel-Strunz 10th (pending) edition ID:6.BB.10

6 : BORATES
B : Diborates
B : Neso-diborates with double tetrahedra B2O(OH)6; 2(2T)
Dana 8th edition ID:26.2.1.1

26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
2 : Diborates
Hey's CIM Ref.:9.3.15

9 : Borates
3 : Borates of Ca and Sr
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Type Occurrence of Pentahydroborite

Type Locality:Novofrolovskoye B-Cu deposit, Turjinsk, Turya river, Krasnoturjinsk (Bogolovsk; Krasnotur'insk; Krasnoturyinsk), Ekaterinburgskaya (Sverdlovskaya) Oblast', Middle Urals, Urals Region, Russia
Year of Discovery:1961

Physical Properties of Pentahydroborite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent
Colour:Colourless
Hardness (Mohs):2½

Crystallography of Pentahydroborite

Crystal System:Triclinic

Optical Data of Pentahydroborite

Type:Biaxial (+)
RI values: nα = 1.531 nβ = 1.536 nγ = 1.544
Maximum Birefringence:δ = 0.013

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low
Dispersion:r < v moderate

Chemical Properties of Pentahydroborite

Formula:
CaB
 
2
O(OH)
 
6
 · 2H
 
2
O
Essential elements:B, Ca, H, O
All elements listed in formula:B, Ca, H, O

Relationship of Pentahydroborite to other Species

Related Minerals - Nickel-Strunz Grouping):
6.BB.05Pinnoite
Mg[B
 
2
O
 
5
] · 3H
 
2
O
Related Minerals - Hey's Index Grouping:
9.3.1Calciborite
Ca[B
 
2
O
 
4
]
9.3.2Sibirskite
Ca
 
2
[B
 
2
O
 
5
] · H
 
2
O
9.3.3Fabianite
CaB
 
3
O
 
5
OH
9.3.4Uralborite
Ca
 
2
[B
 
3
O
 
3
(OH)
 
5
·OB(OH)
 
3
]
9.3.5Vimsite
CaB
 
2
O
 
2
(OH)
 
4
9.3.6Olshanskyite
Ca
 
3
[OH|{B(OH)
 
4
}
 
2
]
 
2
9.3.7Frolovite
Ca[B(OH)
 
4
]
 
2
9.3.8Korzhinskite
CaB
 
2
O
 
4
·H
 
2
O
9.3.9Tyretskite
Ca
 
2
B
 
5
O
 
9
OH·H
 
2
O
9.3.10Nifontovite
CaB
 
2
O
 
4
·2.3H
 
2
O
9.3.12Inyoite
Ca(H
 
4
B
 
3
O
 
7
)(OH) · 4H
 
2
O
9.3.13Gowerite
Ca[B
 
5
O
 
8
(OH)][B(OH)
 
3
]·3H
 
2
O
9.3.14Colemanite
Ca[B
 
3
O
 
4
(OH)
 
3
] · H
 
2
O
9.3.16Hexahydroborite
Ca[B(OH)
 
4
]
 
2
 · 6H
 
2
O
9.3.17Meyerhofferite
Ca
 
2
(H
 
3
B
 
3
O
 
7
)
 
2
 · 4H
 
2
O
9.3.18Priceite
Ca
 
2
B
 
5
O
 
7
(OH)
 
5
·H
 
2
O
9.3.19Ginorite
Ca
 
2
B
 
14
O
 
23
·8H
 
2
O
9.3.20Probertite
NaCaB
 
5
O
 
7
(OH)
 
4
·3H
 
2
O
9.3.21Ulexite
NaCa[B
 
5
O
 
6
(OH)
 
6
] · 5H
 
2
O
9.3.22Hydroboracite
CaMg[B
 
3
O
 
4
(OH)
 
3
]
 
2
 · 3H
 
2
O
9.3.23Inderborite
CaMg(H
 
3
B
 
3
O
 
7
)
 
2
 · 8H
 
2
O
9.3.24Wardsmithite
Ca
 
5
Mg[B
 
4
O
 
7
]
 
6
 · 30H
 
2
O
9.3.25Henmilite
Ca
 
2
Cu[(OH)
 
2
|B(OH)
 
4
]
 
2
9.3.26Strontioborite
SrB
 
8
O
 
11
(OH)
 
4
9.3.27Veatchite
Sr
 
2
B
 
11
O
 
16
(OH)
 
5
·H
 
2
O
9.3.28Veatchite-A
Sr
 
2
B
 
11
O
 
16
(OH)
 
5
·H
 
2
O
9.3.29 P-Veatchite
9.3.30 Balavinskite
Sr
 
2
B
 
6
O
 
11
·4H
 
2
O
9.3.31Tunellite
SrB
 
6
O
 
9
(OH)
 
2
·3H
 
2
O
9.3.32Strontioginorite
(Sr,Ca)
 
2
B
 
14
O
 
23
·8H
 
2
O

Other Names for Pentahydroborite

German names:
Pentahydroborit
Russian names:
Пентагидроборит
Spanish names:
Pentahydroborita

Other Information

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 Pentahydroborite

Reference List:American Mineralogist (1962): 47: 1482.

Soviet Physics – Crystallography: 22: 35-36.

American Mineralogist (1986): 71: 1234.

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

Articles/Blogs about Pentahydroborite

Internet Links for Pentahydroborite

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    Localities for Pentahydroborite

    (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.
    Japan
     
    • Honshu Island
      • Chugoku Region
        • Okayama Prefecture
          • Takahashi
            • Bitchu-cho (Bicchu-cho)
    		Mineralogical Record: 27: 306.
    Russia
     
    • Eastern-Siberian Region
      • Transbaikalia (Zabaykalye)
        • Buriatia (Buryatia) Republic
          • Vitim Plateau
    		[AmMin 85:1322]
    • Urals Region
      • Middle Urals
        • Ekaterinburgskaya (Sverdlovskaya) Oblast'
          • Krasnoturjinsk (Bogolovsk; Krasnotur'insk; Krasnoturyinsk)
            • Turya river
              • Turjinsk
    		[AmMin 85:1322]
    Serbia
     
    • Jarandol Basin
      • Balevats
    		S. V. Malinko et al.: New Data on Minerals 39:26-31 (200)
    Mineral and/or Locality
    Google
     
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