Mindat Logo
Home Page Log In Message Board The Mindat Directory
Register Search Pages Chat Now! (2 online) Mindat Auctions

Pentagonite

Big Photo

Wagholi Quarry, Wagholi, Pune District (Poonah District), Maharashtra, India
© JM. Johannet

Show Pentagonite Photos (57)
Formula:
Ca(VO)Si
 
4
O
 
10
·4H
 
2
O
System:OrthorhombicColour:Greenish blue
Hardness:3 - 4
Name:For the pseudosymetrical five-fold habit
Dimorph of:Cavansite


Structurally related to plumbophyllite.

Classification of Pentagonite

IMA status:Approved
Strunz 8th edition ID:8/H.36-20
Nickel-Strunz 10th (pending) edition ID:9.EA.55

9 : SILICATES (Germanates)
E : Phyllosilicates
A : Single nets of tetrahedra with 4-, 5-, (6-), and 8-membered rings
Dana 8th edition ID:74.3.7.2

74 : PHYLLOSILICATES Modulated Layers
3 : Modulated Layers with joined strips
Hey's CIM Ref.:14.14.2

14 : Silicates not Containing Aluminum
14 : Silicates of V and Bi
mindat.org URL:http://www.mindat.org/min-3152.html
Please feel free to link to this page.

Type Occurrence of Pentagonite

Type Locality:Owyhee Dam, Lake Owyhee State Park, Malheur Co., Oregon, USA
Year of Discovery:1973

Occurrences of Pentagonite

Geological Setting:Fracture filling in tuffs and basalts.

Physical Properties of Pentagonite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent
Colour:Greenish blue
Streak:Light blue
Hardness (Mohs):3 - 4
Tenacity:Brittle
Cleavage:Distinct/Good
Good on {010}
Density (calculated):2.33 g/cm3

Crystallography of Pentagonite

Crystal System:Orthorhombic
Class (H-M):mm2 - Pyramidal
Cell Parameters:a = 10.298(4) Å, b = 13.999(7) Å, c = 8.891(2) Å
Ratio:a:b:c = 0.736 : 1 : 0.635
Unit Cell Volume:V 1,281.74 ų (Calculated from Unit Cell)
Z:4
Morphology:Prismatic
Twinning:Cyclical by reflection accross {110}

Optical Data of Pentagonite

Type:Biaxial (-)
RI values: nα = 1.533 nβ = 1.544 nγ = 1.547
2V:Measured: 50° , Calculated: 54°
Maximum Birefringence:δ = 0.014

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low
Dispersion:r > v strong
Pleochroism:Visible
Comments:X=Z= colorles
Y= blue

Chemical Properties of Pentagonite

Formula:
Ca(VO)Si
 
4
O
 
10
·4H
 
2
O
Essential elements:Ca, H, O, Si, V
All elements listed in formula:Ca, H, O, Si, V

Relationship of Pentagonite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
9.EA.05Cuprorivaite
CaCu[Si
 
4
O
 
10
]
9.EA.05Gillespite
BaFe
2+
 
[Si
 
4
O
 
10
]
9.EA.05Effenbergerite
BaCu[Si
 
4
O
 
10
]
9.EA.05Wesselsite
SrCu[Si
 
4
O
 
10
]
9.EA.10Ekanite
(Ca,Fe
2+
 
,Pb)
 
2
(Th,U)[Si
 
8
O
 
20
]
9.EA.15Apophyllite-(KF)
KCa
 
4
[(F,OH)|Si
 
8
O
 
20
] · 8H
 
2
O
9.EA.15Apophyllite-(KOH)
KCa
 
4
[(OH,F)|Si
 
8
O
 
20
] · 8H
 
2
O
9.EA.15Apophyllite-(NaF)
NaCa
 
4
[F|Si
 
8
O
 
20
] · 8H
 
2
O
9.EA.20Magadiite
NaSi
 
7
O
 
13
(OH)
 
3
·3H
 
2
O
9.EA.25Dalyite
K
 
2
ZrSi
 
6
O
 
15
9.EA.25Davanite
K
 
2
TiSi
 
6
O
 
15
9.EA.30Sazhinite-(Ce)
Na
 
3
Ce[Si
 
6
O
 
15
] · 6H
 
2
O
9.EA.30Sazhinite-(La)
Na
 
3
La[Si
 
6
O
 
15
] · 2H
 
2
O
9.EA.35Armstrongite
CaZr[Si
 
6
O
 
15
]·3H
 
2
O
9.EA.40Okenite
CaSi
 
2
O
 
5
·2H
 
2
O
9.EA.45Nekoite
Ca
 
3
Si
 
6
O
 
15
·7H
 
2
O
9.EA.50Cavansite
Ca(VO)Si
 
4
O
 
10
·4H
 
2
O
9.EA.60Penkvilksite
Na
 
4
Ti
 
2
Si
 
8
O
 
22
·4H
 
2
O
9.EA.60Tumchaite
Na
 
2
Zr(Si
 
4
O
 
11
)·2H
 
2
O
9.EA.65Nabesite
Na
 
2
BeSi
 
4
O
 
10
 * 4 H
 
2
O
9.EA.70Ajoite
(K,Na)Cu
 
7
[(OH)
 
6
|AlSi
 
9
O
 
24
] · 3H
 
2
O
9.EA.75Zeravshanite
Cs
 
4
Na
 
2
Zr
 
3
[Si
 
18
O
 
45
](H
 
2
O)
 
2
9.EA.80Bussyite-(Ce)
(Ce,REE)
 
3
(Na,H
 
2
O)
 
6
MnSi
 
9
Be
 
5
(O,OH)
 
30
F
 
4
9.EA.85Plumbophyllite
Pb
 
2
Si
 
4
O
 
10
·H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
14.14.1Cavansite
Ca(VO)Si
 
4
O
 
10
·4H
 
2
O
14.14.3Goldmanite
Ca
 
3
(V
3+
 
,Al,Fe
3+
 
)
 
2
[SiO
 
4
]
 
3
14.14.4Haradaite
SrVSi
 
2
O
 
7
14.14.5Saneroite
Na
 
2
(Mn,Mn)
 
10
Si
 
11
VO
 
34
(OH)
 
4
14.14.6Erlianite
(Fe,Mg)
 
4
(Fe,V)
 
2
Si
 
6
O
 
15
(OH,O)
 
8
14.14.7Eulytine
Bi
 
4
[SiO
 
4
]
 
3
14.14.8Bismutoferrite
Fe
3+
2
Bi[OH|(SiO
 
4
)
 
2
]

Other Names for Pentagonite

Synonyms:
IMA1971-039
Other Languages:
German:Pentagonit
Russian:Пентагонит
Spanish:Pentagonita

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 Pentagonite

Reference List:American Mineralogist (1973): 58: 412-424.

Mineralogical Record (2003): 34: 40-43.

Ishida, N., Kimata, M., Nishida, N., Hatta, T., Shimizu, M., Akasaka, T. (2009): Polymorphic relation between cavansite and pentagonite: Genetic implications of oxonium ion in cavansite. Journal of Mineralogical and Petrological Sciences, 104, 241-252

Internet Links for Pentagonite

Search Engines:
  • Look for Pentagonite on Google
  • Look for Pentagonite images on Google
    • External Links:
  • Look for Pentagonite on Webmineral
  • Look for Pentagonite on Athena Mineralogy
  • Look for Pentagonite on Wikipedia
  • Look for Pentagonite on Mineralien Atlas
  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Pentagonite in the Natural History Museum (London) online catalogue
  • Pentagonite details from Handbook of Mineralogy (PDF)
    • Mineral Dealers:
  • Top quality minerals from Kristalle of California
  • Search for - Pentagonite - on e-Rocks Mineral Sales & Auctions
  • Find Pentagonite on www.crystalclassics.co.uk
  • Buy Fine Minerals from mineralsweb.com
  • SpiriferMinerals.com - high quality specimens
  • Fine Minerals from Dan Weinrich Minerals
  • Wright's Rock Shop - excellent mineral specimens since 1970
  • Fabre Minerals - search for Pentagonite specimens
  • High-end worldwide specimens & outstanding customer service
  • The Arkenstone - Fine Minerals
  • DAKOTA MATRIX offers Cabinet and Rare Species from Worldwide Localities.
  • Buy fine minerals and gemstones from Pala International
    • Jobs:
  • Mining & Geology Jobs

    • Page Sponsor

    Sponsorship:This page is currently not sponsored. Click here to sponsor this page.

    Localities for Pentagonite

    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.
    (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.
    India
     
    • Maharashtra
      • Pune District (Poonah District)
        • Lonavale (Lonavala)
    		Min Rec 2007 38:185-189
        • Wagholi
    		http://www.irocks.com/pentag.htm
    USA
     
    • Oregon
      • Malheur Co.
        • Lake Owyhee State Park
    		Amer.Min.(1973) 58, 405-411 and 412-424
    Mineral and/or Locality
    Google
     
    www.mindat.org Web
    Copyright © Jolyon Ralph and Ida Chau 1993-2009. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them.Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. If you would like to add information to improve the quality of our database, then click here to register. Current server date and time: 28th Oct 2009 13:25:14