Volkonskoite Mineral Data

Volkonskoite Mineral Data +

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General Volkonskoite Information

Chemical Formula:

Ca0.3(Cr+++,Mg,Fe+++)2(Si,Al)4O10(OH)2·4(H2O)

Composition:

Molecular Weight = 475.69 gm

Calcium 0.84 % Ca 1.18 % CaO

Magnesium 4.60 % Mg 7.63 % MgO

Aluminum 2.84 % Al 5.36 % Al₂O₃

Chromium 13.12 % Cr 19.17 % Cr₂O₃

Iron 3.52 % Fe 5.04 % Fe₂O₃

Silicon 20.66 % Si 44.21 % SiO₂

Hydrogen 1.95 % H 17.42 % H₂O

Oxygen 52.47 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca_0.1Mg_0.1Cr_1.2Mg_0.8Fe³⁺_0.3Si_3.5Al_0.5O₁₀(OH)₂·3.6(H₂O)

Environment:

Epignetic mineral in sandstones, conglomerates, and red beds, commonly filling voids from the decomposition of organic material.

IMA Status:

Valid Species (Pre-IMA) 1830

Locality:

Mt. Efimiatsk and elsewhere in the Okhansk region, Middle Kama River area, Perm Basin, Ural Mountians, Russia. Link to MinDat.org Location Data.

Name Origin:

Named for Prince A. Volkonskoi, Minister of the Imperial Court, Russia.

Synonym:

Volchonskoite

Wolchonskoite

Volkonskoite Image

Images:

Volkonskoite

Comments: Specimen of massive, green volkonskoite.
Location: Efimyatskaja Perm, Ural Mts., Russia. Scale: 1.1 x 1 cm.
© John Veevaert

Volkonskoite Crystallography

Axial Ratios:

a:b:c =0.5771:1:1.6107

Cell Dimensions:

a = 5.16, b = 8.94, c = 14.4, Z = 2; beta = 90° V = 664.28 Den(Calc)= 2.38

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/m

Physical Properties of Volkonskoite

Cleavage:

[001] Perfect

Color:

Yellow, Olive green, Bright green.

Density:

2 - 2.5, Average = 2.25

Diaphaniety:

Subopaque

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Scaly - Morphology like fish scales.

Hardness:

1.5-2 - Talc-Gypsum

Luster:

Resinous

Streak:

blue green

Optical Properties of Volkonskoite

Gladstone-Dale:

CI meas= 0.005 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.06 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2365,KPDmeas= 0.2501,KC= 0.2515

Optical Data:

Biaxial (-), a=1.551-1.56, b=1.564, g=1.569, bire=0.0090-0.0180, 2V(Calc)=62-84, 2V(Meas)=small.

Calculated Properties of Volkonskoite

Electron Density:

r_electron=2.26 gm/cc
note: r_Volkonskoite=2.25 gm/cc.

Fermion Index

Fermion Index = 0.02772
Boson Index = 0.97228

Photoelectric:

PE_Volkonskoite= 4.99 barns/electron
U=PE_Volkonskoite x r_electron= 11.29 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Volkonskoite is Not Radioactive

Volkonskoite Classification

Dana Class:

71.3.1a.4 (71)Phyllosilicate Sheets of Six-Membered Rings

(71.3)with 2:1 clays

(71.3.1a)Smectite group (Dioctahedral Smectites)

71.3.1a.1 Beidellite Na0.5Al2(Si3.5Al0.5)O10(OH)2·n(H2O) C 2/m or ORTH 2/m

71.3.1a.2 Montmorillonite (Na,Ca)0,3(Al,Mg)2Si4O10(OH)2·n(H2O) C 2/m 2/m

71.3.1a.3 Nontronite Na0.3Fe2(Si,Al)4O10(OH)2·n(H2O) C 2/m 2/m

71.3.1a.4 Volkonskoite Ca0.3(Cr,Mg,Fe)2(Si,Al)4O10(OH)2·4(H2O) C 2/m 2/m

71.3.1a.5 Swinefordite (Li,Ca0.5,Na)0.72(Li,Al,Mg)2.66(Si,Al)4O10(OH,F)2·2(H2O) C 2/m (MON or ORTH) 2/m

Strunz Class:

VIII/H.19-50 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica like with [Si4O10]4- and related groups

VIII/H.19 - Brammallite ? - Yakhontovite series

VIII/H.19-10 Brammallite* (Na,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] C 2/c 2/m

VIII/H.19-10a Brinrobertsite! (Na,K,Ca)x(Al,Fe,Mg)4(Si,Al)8O20(OH)4·3.54(H2O)[x=0.35,n=3.54] pseudo 2/m 2/m

VIII/H.19-15 Illite* (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] C 2/m 2/m

VIII/H.19-20 Montmorillonite (Na,Ca)0,3(Al,Mg)2Si4O10(OH)2·n(H2O) C 2/m 2/m

VIII/H.19-30 Beidellite Na0.5Al2(Si3.5Al0.5)O10(OH)2·n(H2O) C 2/m or ORTH 2/m

VIII/H.19-40 Nontronite Na0.3Fe2(Si,Al)4O10(OH)2·n(H2O) C 2/m 2/m

VIII/H.19-50 Volkonskoite Ca0.3(Cr,Mg,Fe)2(Si,Al)4O10(OH)2·4(H2O) C 2/m 2/m

VIII/H.19-60 Swinefordite (Li,Ca0.5,Na)0.72(Li,Al,Mg)2.66(Si,Al)4O10(OH,F)2·2(H2O) C 2/m (MON or ORTH) 2/m

VIII/H.19-70 Yakhontovite (Ca,K)0.5(Cu,Fe,Mg)2Si4O10(OH)2·3(H2O) C 2/m 2/m

Other Volkonskoite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic2)

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Volkonskoite

Ca0.3(Cr+++,Mg,Fe+++)2(Si,Al)4O10(OH)2·4(H2O)
Dana No: 71.3.1a.4 Strunz No: VIII/H.19-50
Locality:

Notes: