Pentagonite Mineral Data

Pentagonite Mineral Data +

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General Pentagonite Information

Chemical Formula:

Ca(VO)Si4O10·4(H2O)

Composition:

Molecular Weight = 451.42 gm

Calcium 8.88 % Ca 12.42 % CaO

Vanadium 11.28 % V 20.15 % V₂O₅

Silicon 24.89 % Si 53.24 % SiO₂

Hydrogen 1.79 % H 15.96 % H₂O

Oxygen 53.16 % O

______ ______

100.00 % 101.77 % = TOTAL OXIDE

Empirical Formula:

CaV⁵⁺Si₄O₁₁·4(H₂O)

Environment:

Alteration product occurring in basalts and tuffs.

IMA Status:

Approved IMA 1973

Locality:

Lake Owyhee State Park, Malheur County, and Goble, Columbia County, Oregon, USA. Link to MinDat.org Location Data.

Name Origin:

Named from the Greek, penta, "five" and angle in allusion to the fiveling twins common in this species.

Synonym:

ICSD 10262

PDF 25-181

Pentagonite Image

Images:

Pentagonite

Comments: Blue, crystalline aggregate of pentagonite on zeolite.
Location: Wagholi quarries, Poona, India. Scale: Grain size 1.2 cm.
© Tom Loomis / Dakota Matrix

Pentagonite Crystallography

Axial Ratios:

a:b:c =0.7356:1:0.635

Cell Dimensions:

a = 10.298, b = 13.999, c = 8.89, Z = 4; V = 1,281.60 Den(Calc)= 2.34

Crystal System:

Orthorhombic - PyramidalH-M Symbol (mm2) Space Group: Ccm21

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 3.755(1), 3.92(1), 6.071(1),

Forms:

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Forms: [ 2 0 1] [ 1 1 0] [ 0 0 1]

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Crystal Structure:

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Evans H T , American Mineralogist , 58 (1973) p.412-424, The crystal structures of cavansite and pentagonite

Physical Properties of Pentagonite

Cleavage:

[010] Good

Color:

Greenish blue.

Density:

2.33

Diaphaniety:

Transparent

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Habit:

Rosette - Bundled tabular aggregates resembling rose flower petals.

Habit:

Twinning Common - Crystals are usually twinned.

Hardness:

3-4 - Calcite-Fluorite

Luster:

Vitreous (Glassy)

Streak:

bluish white

Optical Properties of Pentagonite

Gladstone-Dale:

CI meas= 0.102 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.106 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2321,KPDmeas= 0.2331,KC= 0.2596

Optical Data:

Biaxial (-), a=1.533-1.54, b=1.544-1.545, g=1.547-1.55, bire=0.0100-0.0140, 2V(Calc)=54-88, 2V(Meas)=50. Dispersion r < v extreme.

Pleochroism (x):

colorless.

Pleochroism (y):

blue.

Pleochroism (z):

colorless.

Calculated Properties of Pentagonite

Electron Density:

r_electron=2.34 gm/cc
note: r_Pentagonite=2.33 gm/cc.

Fermion Index

Fermion Index = 0.01228
Boson Index = 0.98772

Photoelectric:

PE_Pentagonite= 4.15 barns/electron
U=PE_Pentagonite x r_electron= 9.71 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Pentagonite is Not Radioactive

Pentagonite Classification

Dana Class:

74.3.7.2 (74)Phyllosilicate Modulated Layers

(74.3)with joined strips

(74.3.7)V phyllosilicates

74.3.7.1 Cavansite Ca(VO)Si4O10·4(H2O) Pcmn 2/m 2/m 2/m

74.3.7.2 Pentagonite Ca(VO)Si4O10·4(H2O) Ccm21 mm2

Strunz Class:

VIII/H.36-20 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica minerals with other simple layers, [Si6O15]6- and others

VIII/H.36 - Cavansite - Pentagonite series

VIII/H.36-10 Cavansite Ca(VO)Si4O10·4(H2O) Pcmn 2/m 2/m 2/m

VIII/H.36-20 Pentagonite Ca(VO)Si4O10·4(H2O) Ccm21 mm2

Other Pentagonite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Dana8)

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Print or Cut-and-Paste your Pentagonite Specimen Label here :

Pentagonite

Ca(VO)Si4O10·4(H2O)
Dana No: 74.3.7.2 Strunz No: VIII/H.36-20
Locality:

Notes: