Rectorite Mineral Data

Rectorite Mineral Data +

General Rectorite Information

Chemical Formula:

(Na,Ca)Al4(Si,Al)8O20(OH)4·2(H2O)

Composition:

Molecular Weight = 784.18 gm

Potassium 0.50 % K 0.60 % K₂O

Sodium 1.76 % Na 2.37 % Na₂O

Calcium 1.53 % Ca 2.15 % CaO

Aluminum 20.64 % Al 39.01 % Al₂O₃

Silicon 21.49 % Si 45.97 % SiO₂

Hydrogen 1.03 % H 9.19 % H₂O

Oxygen 53.05 % O

______ ______

100.00 % 99.29 % = TOTAL OXIDE

Empirical Formula:

Na_0.6Ca_0.3K_0.1Al₆Si₆O₂₀(OH)₄·2(H₂O)

Environment:

Alteration of potassic feldspars or diagenesis of muscovite.

IMA Status:

Valid Species (Pre-IMA) 1891

Locality:

Blue Mountain district, Marble, Garland County, Arkansas, USA. Link to MinDat.org Location Data.

Name Origin:

Named for E. W. Rector (1849-1917), legislator and lawyer of Hot Springs, Arkansas, USA.

Synonym:

Ca-Rectorite

K-Rectorite

Na-Rectorite

Smectite

Tarasovite

Rectorite Image

Images:

Rectorite

Comments: Blue Mountain District, Marble Township, Garland Co., Arkansas, USA.
Location: Five pieces of leather-like fragments of rectorite in twisted, irregular shapes. Scale: Specimen size 1-4 cm.
© John Betts - Fine Minerals

Rectorite Crystallography

Axial Ratios:

a:b:c =0.5777:1:2.6858

Cell Dimensions:

a = 5.13, b = 8.88, c = 23.85, Z = 2; beta = 96.3° V = 1,079.91 Den(Calc)= 2.41

Crystal System:

MonoclinicSpace Group: Unk

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

By Intensity(I/I_o): 4.45(1), 2.55(0.7), 1.492(0.4),12.2(0.4), 3.15(0.3), 4.99(0.3), 26.4(0.3), 2.44(0.1),

Physical Properties of Rectorite

Cleavage:

[001] Perfect

Color:

Yellowish white, White.

Fracture:

Flexible - Flexible fragments.

Habit:

Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite).

Hardness:

1-2 - Between Talc and Gypsum

Luster:

Earthy (Dull)

Streak:

white

Optical Properties of Rectorite

Gladstone-Dale:

CI calc= -0.034 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2252,KC= 0.2178

Optical Data:

Biaxial (-), a=1.519, b=1.55, g=1.559, bire=0.0400, 2V(Calc)=54, 2V(Meas)=5-20. Dispersion r > v.

Calculated Properties of Rectorite

Electron Density:

r_electron=2.41 gm/cc
note: r_Rectorite=2.41 gm/cc.

Fermion Index

Fermion Index = 0.01031
Boson Index = 0.98969

Photoelectric:

PE_Rectorite= 1.72 barns/electron
U=PE_Rectorite x r_electron= 4.14 barns/cc.

Radioactivity:

GRapi = 7.20 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Rectorite - barely detectable

Rectorite Classification

Dana Class:

71.4.2.7 (71)Phyllosilicate Sheets of Six-Membered Rings

(71.4)interlayered 1:1, 2:1, and octahedra

(71.4.2)Interstratified Chlorite-Smectite group

71.4.2.1 Dozyite (Mg7Al2)(Si4Al2)O15(OH)12 Cm m

71.4.2.2 Lunijianlaite LiAl6(Si7Al)O20(OH)10 Unk Mono

71.4.2.3 Saliotite Na0.5Li0.5Al3AlSi3O10(OH)5 C 2/m 2/m

71.4.2.4 Tosudite Na0,5(Al,Mg)6(Si,Al)8O18(OH)12·5(H2O) Unk Ortho

71.4.2.5 Corrensite (Ca,Na,K)(Mg,Fe,Al)9(Si,Al)8O20(OH)10·n(H2O) Unk Ortho

71.4.2.6 Kulkeite Na0.35Mg8AlSi7O20(OH)10 Unk Mono

71.4.2.7 Rectorite (Na,Ca)Al4(Si,Al)8O20(OH)4·2(H2O) Unk Mono

71.4.2.8 Aliettite [Mg3Si4O10(OH)2](Ca0.5,Na)0.33(Al,Mg,Fe)2-3(Si,Al)4O10(OH)2·n(H2O) Unk Mono

71.4.2.9 Glagolevite! NaMg6[Si3AlO10](OH,O)8·H2O C1 1

Strunz Class:

VIII/H.18-30 VIII - Silicates

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

VIII/H.18 - Smectite/Montmorillonite group

VIII/H.18-05 Lunijianlaite LiAl6(Si7Al)O20(OH)10 Unk Mono

VIII/H.18-07 Saliotite Na0.5Li0.5Al3AlSi3O10(OH)5 C 2/m 2/m

VIII/H.18-10 Kulkeite Na0.35Mg8AlSi7O20(OH)10 Unk Mono

VIII/H.18-20 Aliettite [Mg3Si4O10(OH)2](Ca0.5,Na)0.33(Al,Mg,Fe)2-3(Si,Al)4O10(OH)2·n(H2O) Unk Mono

VIII/H.18-30 Rectorite (Na,Ca)Al4(Si,Al)8O20(OH)4·2(H2O) Unk Mono

VIII/H.18-50 Tosudite Na0,5(Al,Mg)6(Si,Al)8O18(OH)12·5(H2O) Unk Ortho

VIII/H.18-60 Corrensite (Ca,Na,K)(Mg,Fe,Al)9(Si,Al)8O20(OH)10·n(H2O) Unk Ortho

VIII/H.18-70 Hydrobiotite [K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2]·[(Mg,Fe,Al)3(Si,Al)4O10(OH)2·4(H2O)] C 2/m 2/m

Other Rectorite Information

References:

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

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Rectorite

(Na,Ca)Al4(Si,Al)8O20(OH)4·2(H2O)
Dana No: 71.4.2.7 Strunz No: VIII/H.18-30
Locality:

Notes: