Magadiite Mineral Data

Magadiite Mineral Data +

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General Magadiite Information

Chemical Formula:

NaSi7O13(OH)3·4(H2O)

Composition:

Molecular Weight = 550.66 gm

Sodium 4.17 % Na 5.63 % Na₂O

Silicon 35.70 % Si 76.38 % SiO₂

Hydrogen 2.01 % H 17.99 % H₂O

Oxygen 58.11 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

NaSi₇O₁₃(OH)₃·4(H₂O)

Environment:

Associated with other rare alkalic minerals in brines with high Ph and silica content.

IMA Status:

Approved IMA 1967

Locality:

Lake Magadi, Olduvai Gorge, Kenya. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Magadiite Image

Images:

Magadiite Rhodesite

Comments: Earth pale tan massive magadiite with dark yellow crystalline rhodesite.
Location: East Fork, Trinity River, Trinity County, California, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Magadiite Crystallography

Axial Ratios:

a:b:c =1:1:2.1641

Cell Dimensions:

a = 7.25, b = 7.25, c = 15.69, Z = 2; beta = 96.8° V = 818.90 Den(Calc)= 2.23

Crystal System:

MonoclinicSpace Group: Unk

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

By Intensity(I/I_o): 15.41(1), 3.435(0.8), 3.146(0.5),

Physical Properties of Magadiite

Color:

White.

Diaphaniety:

Transparent

Habit:

Microscopic Crystals - Crystals visible only with microscopes.

Habit:

Platy - Sheet forms (e.g. micas).

Habit:

Powdery - Forms a loose, poorly-coherent pulverulent mass.

Hardness:

2 - Gypsum

Luster:

Vitreous - Dull

Streak:

white

Optical Properties of Magadiite

Gladstone-Dale:

CI calc= 0.087 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2108,KC= 0.2307

Optical Data:

Biaxial (?), a=1.47

Calculated Properties of Magadiite

Electron Density:

r_electron=2.27 gm/cc
note: r_Magadiite=2.23 gm/cc.

Fermion Index

Fermion Index = 0.01695
Boson Index = 0.98305

Photoelectric:

PE_Magadiite= 1.48 barns/electron
U=PE_Magadiite x r_electron= 3.36 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Magadiite is Not Radioactive

Magadiite Classification

Dana Class:

78.7.12.1 (78)Unclassified silicates

(78.7)wholly unclassified silicates

(78.7.12)Dana Group

78.7.12.1 Magadiite NaSi7O13(OH)3·4(H2O) Unk Mono

Strunz Class:

VIII/H.39-20 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica minerals with tetrahedral-double layers and related structures

VIII/H.39 - Silhydrite - Vertumnite series

VIII/H.39-10 Silhydrite 3SiO2·(H2O) P??? Ortho

VIII/H.39-20 Magadiite NaSi7O13(OH)3·4(H2O) Unk Mono

VIII/H.39-30 Stratlingite Ca2Al[(OH)6AlSiO2-3(OH)4-3]·2,5(H2O) R 3m 3 2/m

VIII/H.39-40 Vertumnite Ca8Al4(Al4Si5)O12[(OH)36·10(H2O) P 2₁/a 2/m

Other Magadiite 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 Magadiite Specimen Label here :

Magadiite

NaSi7O13(OH)3·4(H2O)
Dana No: 78.7.12.1 Strunz No: VIII/H.39-20
Locality:

Notes: