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Cavansite

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Formula:
Ca(VO)Si4O10 · 4H2O
System:
Orthorhombic
Colour:
Greenish-blue to blue
Lustre:
Vitreous
Hardness:
3 - 4
Name:
For the elements calcium, vanadium, and silicon in the composition.
Dimorph of:
Ishida et al. (2009) suggest that cavansite is a low-temperature form and pentagonite a high-temperature from.

Classification of Cavansite

Approved 1967
9.EA.50

9 : SILICATES (Germanates)
E : Phyllosilicates
A : Single nets of tetrahedra with 4-, 5-, (6-), and 8-membered rings
74.3.7.1

74 : PHYLLOSILICATES Modulated Layers
3 : Modulated Layers with joined strips
14.14.1

14 : Silicates not Containing Aluminum
14 : Silicates of V and Bi
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First Recorded Occurrence of Cavansite

Year of Discovery:
1967

Occurrences of Cavansite

Geological Setting:
Basalt vesicular filling.

Physical Properties of Cavansite

Vitreous
Diaphaneity (Transparency):
Transparent
Colour:
Greenish-blue to blue
Hardness (Mohs):
3 - 4
Tenacity:
Brittle
Cleavage:
Distinct/Good
Good on {010}
Density:
2.21 - 2.31 g/cm3 (Measured)    2.33 g/cm3 (Calculated)

Crystallography of Cavansite

Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Cell Parameters:
a = 9.792(2) Å, b = 13.644(3) Å, c = 9.629(2) Å
Ratio:
a:b:c = 0.718 : 1 : 0.706
Unit Cell Volume:
V 1,286.45 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Prismatic crystals, spherulitic rosettes.
Comment:
Space group Pcnm.
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Cavansite

Type:
Biaxial (+)
RI values:
nα = 1.542(2) nβ = 1.544(2) nγ = 1.551(2)
2V:
Measured: 52° , Calculated: 58°
Max Birefringence:
δ = 0.009
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Low
Dispersion:
r < v extreme
Pleochroism:
Visible
Comments:
X=Z= colorless
Y= blue

Chemical Properties of Cavansite

Formula:
Ca(VO)Si4O10 · 4H2O
Essential elements:
All elements listed in formula:

Relationship of Cavansite to other Species

9.EA.05CuprorivaiteCaCu[Si4O10]
9.EA.05GillespiteBaFe2+[Si4O10]
9.EA.05EffenbergeriteBaCu[Si4O10]
9.EA.05WesselsiteSrCu[Si4O10]
9.EA.10Ekanite(Ca,Fe2+,Pb)2(Th,U)[Si8O20]
9.EA.15Fluorapophyllite-(K)KCa4(Si8O20)(F,OH) · 8H2O
9.EA.15Hydroxyapophyllite-(K)KCa4(Si8O20)(OH,F) · 8H2O
9.EA.15Fluorapophyllite-(Na)NaCa4(Si8O20)F · 8H2O
9.EA.20MagadiiteNa2Si14O29 · 11H2O
9.EA.25DalyiteK2ZrSi6O15
9.EA.25DavaniteK2TiSi6O15
9.EA.30Sazhinite-(Ce)Na3Ce[Si6O15] · 6H2O
9.EA.30Sazhinite-(La)Na3La[Si6O15] · 2H2O
9.EA.35ArmstrongiteCaZr[Si6O15] · 3H2O
9.EA.40OkeniteCaSi2O5 · 2H2O
9.EA.45NekoiteCa3Si6O15·7H2O
9.EA.55PentagoniteCa(VO)Si4O10 · 4H2O
9.EA.60PenkvilksiteNa4Ti2Si8O22 · 4H2O
9.EA.60TumchaiteNa2Zr(Si4O11) · 2H2O
9.EA.65NabesiteNa2BeSi4O10 · 4H2O
9.EA.70Ajoite(K,Na)Cu7AlSi9O24(OH)6 · 3H2O
9.EA.75ZeravshaniteNa2Cs4Zr3[Si18O45]*2H2O
9.EA.80Bussyite-(Ce)(Ce,REE)3(Na,H2O)6MnSi9Be5(O,OH)30F4
9.EA.85PlumbophyllitePb2Si4O10 · H2O
14.14.2PentagoniteCa(VO)Si4O10 · 4H2O
14.14.3GoldmaniteCa3V23+(SiO4)3
14.14.4HaradaiteSrVSi2O7
14.14.5SaneroiteNa2(Mn,Mn)10Si11VO34(OH)4
14.14.6Erlianite(Fe,Mg)4(Fe,V)2Si6O15(OH,O)8
14.14.7EulytineBi4(SiO4)3
14.14.8BismutoferriteFe23+Bi(SiO4)2(OH)

Other Names for Cavansite

Name in Other Languages:
Dutch:Cavansiet
German:Cavansit
Italian:Cavansite
Low Saxon:Cavansit
Polish:Cavansyt
Spanish:Cavansita

Other Information

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 Cavansite

Reference List:
Staples, L.W., H.T. Evans, Jr., and J.R. Lindsay (1973): Cavansite and pentagonite, new dimorphous calcium vanadium silicate minerals from Oregon. Amer. Mineral., 58, 405-411.

Evans, H.T., Jr. (1973): The crystal structures of cavansite and pentagonite. Amer. Mineral., 58, 412-424.

Wilke, H.-J., G. Schnorrer-Köhler, and A. Bahle (1989): Cavansit aus Indien. Lapis, 14 (1), 39-42 (in German).

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 Cavansite

Specimens:
The following Cavansite specimens are currently listed for sale on minfind.com.

Localities for Cavansite

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 for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? 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.
Brazil
 
  • Rio Grande do Sul
    • Morro Reuter
Lapis 29(9), 41-42 (2004)
Iceland
http://en.ni.is/geology/minerals/cavansite/
India
 
  • Maharashtra
    • Pune District (Poonah District)
      • Lonavale (Lonavala)
Praszkier, T. & Siuda, R. (2007): The Lonavala Quarry, Pune District, Maharashtra, India. Mineralogical Record 38: 185-189
      • Talegaon
Praszkier, T. (2009): Cavansit und Pentagonit aus Indien. Mineralien-Welt 20 (6), 16-25.
Praszkier, T. (2009): Cavansit und Pentagonit aus Indien. Mineralien-Welt 20 (6), 16-25.
[www.johnbetts-fineminerals.com]
http://www.hedegaard.com/Localities/India/Wagholi/Wagholi.html
Rocks & Min.:64(5):413.
Min Rec 2007 38:185-189
    • Satara District
Min Rec 2007 38:185-189
    • Sindhudurg District
      • Sutarwadi
Min Rec 2007 38:185-189
New Zealand
 
  • North Island
    • Northland
      • Kaipara
        • Aranga
Lapis 29(9), 41-42 (2004)
USA
 
  • Oregon
    • Columbia Co.
      • Goble
Rocks & Minerals: 64(5): 413.
    • Malheur Co.
      • Lake Owyhee State Park
Progr.Ann.Meeting Geol.Soc.Amer.(1967) p. 211
Mineral and/or Locality  
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