Mineralogy Database

Londonite Mineral Data

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General Londonite Information

Help on Chemical  Formula: Chemical Formula: CsAl4Be4(B,Be)12O28
Help on Composition: Composition: Molecular Weight = 808.60 gm
   Cesium      7.89 %  Cs    8.36 % Cs2O
   Potassium   1.84 %  K     2.21 % K2O
   Rubidium    0.95 %  Rb    1.04 % Rb2O
   Sodium      0.09 %  Na    0.11 % Na2O
   Lithium     0.02 %  Li    0.04 % Li2O
   Calcium     0.10 %  Ca    0.14 % CaO
   Manganese   0.07 %  Mn    0.09 % MnO
   Beryllium   5.57 %  Be   15.47 % BeO
   Aluminum   13.28 %  Al   25.09 % Al2O3
   Iron        0.07 %  Fe    0.09 % FeO
   Silicon     0.03 %  Si    0.07 % SiO2
   Boron      14.69 %  B    47.31 % B2O3
   Oxygen     55.40 %  O
             ______        ______ 
             100.00 %      100.03 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Cs0.48K0.38Rb0.09Na0.03Ca0.02Mn2+0.01Al3.98Li0.02Fe2+0.01Be4B10.99Si0.01BeO28
Help on Environment: Environment: Found in miarolitic cavities. Cs-analogue of rhodizite.
Help on IMA Status: IMA Status: Approved IMA 1999 (Dana # Added)
Help on Locality: Locality: Central units or the Antandrokomby, Antsonombato, and Ampanivana granitic pegmatites in Central Madagascar. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for David London (1953-), petrologist at the University of Oklahoma, Oklahoma, USA.
Help on Synonym: Synonym: IMA1999-014
 

Londonite Image

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  Londonite

Comments: A dodecahedral crystal of londonite.
Location: Antandrokomby pegmatite, Manandona valley, Sahatany Valley, Betafo - Antsirabé region, Antananarivo Province, Madagascar. Scale: Crystal size 7 mm.
© Thomas Witzke / Abraxas-Verlag

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  Londonite

Comments: A yellow , lustrous, well developed londonite crystal 1.2 cm. on matrix.
Location: Antandrokomby, Sahatany valley, Madagascar. Scale: Crystal size 1.2 cm.
© Sandro Maggia/Minernet.it

Londonite Crystallography

Help on Cell Dimensions: Cell Dimensions: a = 7.3205, Z = 1; V = 392.30 Den(Calc)= 3.42
Help on Crystal System: Crystal System: Isometric - Hextetrahedral H-M Symbol (4 3m) Space Group: P 43m
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.9898(1)(211), 2.1132(0.7)(222), 2.441(0.5)(300,221),1.7759(0.4)(410,322), 1.9568(0.35)(321), 3.276(0.35)(210), 2.208(0.3),
 

Physical Properties of Londonite

Help on Cleavage: Cleavage: None
Help on Color: Color: Colorless, White, Yellow.
Help on Density: Density: 3.34
Help on Diaphaneity: Diaphaneity: Transparent
Help on Fracture: Fracture: Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.
Help on Habit: Habit: Euhedral Crystals - Occurs as well-formed crystals showing good external form.
Help on Hardness: Hardness: 8 - Topaz
Help on Luster: Luster: Vitreous (Glassy)
Help on Streak: Streak: white
 

Optical Properties of Londonite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= 0 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.024 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2026,KPDmeas= 0.2075,KC= 0.2075
Ncalc = 1.69 - 1.71
Help on Optical Data: Optical Data: Isotropic, n=1.693.
 

Calculated Properties of Londonite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=3.21 gm/cc
note: Specific Gravity of Londonite =3.34 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.08
Boson Index = 0.92
Help on Photoelectric: Photoelectric: PELondonite = 33.04 barns/electron
U=PELondonite x relectron= 106.21 barns/cc.
Help on Radioactivity: Radioactivity:

GRapi = 413.95 (Gamma Ray American Petroleum Institute Units)
Concentration of Londonite per GRapi unit = 0.24 (%)

Estimated Radioactivity from Londonite - barely detectable

 

Londonite Classification

Help on  Dana Class: Dana Class: 25.08.02.02 (25)Anhydrous Borates Containing Hydroxyl or Halogen
  (25.08)Dana Type
  (25.08.02)Dana Group
 
25.08.02.01 Rhodizite (K,Cs)Al4Be4(B,Be)12O28 P 43m 4 3m
 
25.08.02.02 Londonite! CsAl4Be4(B,Be)12O28 P 43m 4 3m
Help on  Strunz Class: Strunz Class: 06.GC.05 06 - BORATES
  06.G - Heptaborates and other Megaborates
  06.GC -Tekto-dodecaborates
 
06.GC.05 Rhodizite (K,Cs)Al4Be4(B,Be)12O28 P 43m 4 3m
 
06.GC.05 Londonite! CsAl4Be4(B,Be)12O28 P 43m 4 3m
 

Other Londonite Information

Help on References: References: NAME( AmMin, Vol 87, p 356) PHYS. PROP.(AmMin, Vol 87, p 356) OPTIC PROP.(AmMin, Vol 87, p 356)
Help on See Also: See Also: Links to other databases for Londonite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - Handbook of Mineralogy (MinSocAm)
7 - Handbook of Mineralogy (UofA)
8 - MinDAT
9 - Mineralienatlas (Deutsch)
10 - Online Mineral Museum
11 - QUT Mineral Atlas
12 - Ruff.Info

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

Londonite

CsAl4Be4(B,Be)12O28
Dana No: 25.08.02.02 Strunz No: 06.GC.05
Locality:

 

Notes:

 

 
   
 


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