Londonite Mineral Data

General Londonite Information

Chemical Formula:

CsAl4Be4(B,Be)12O28

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

Empirical Formula:

Cs_0.48K_0.38Rb_0.09Na_0.03Ca_0.02Mn²⁺_0.01Al_3.98Li_0.02Fe²⁺_0.01Be₄B_10.99Si_0.01BeO₂₈

Environment:

Found in miarolitic cavities. Cs-analogue of rhodizite.

IMA Status:

Approved IMA 1999 (Dana # Added)

Locality:

Central units or the Antandrokomby, Antsonombato, and Ampanivana granitic pegmatites in Central Madagascar. Link to MinDat.org Location Data.

Name Origin:

Named for David London (1953-), petrologist at the University of Oklahoma, Oklahoma, USA.

Synonym:

IMA1999-014

Londonite Image

Images:

Londonite

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

Images:

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

Cell Dimensions:

a = 7.3205, Z = 1; V = 392.30 Den(Calc)= 3.42

Crystal System:

Isometric - HextetrahedralH-M Symbol (4 3m) Space Group: P 43m

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

By Intensity(I/I_o): 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),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

Taxer K J , Buerger M J , Zeitschrift fur Kristallographie , 125 (1967) p.423-436, The crystal struture of rhodizite, Note: name of mineral altered according to IMA decision in 1999, to name the Cs dominant phase: londonite, Locality: Manjaka, Madagascar

Physical Properties of Londonite

Cleavage:

None

Color:

Colorless, White, Yellow.

Density:

3.34

Diaphaneity:

Transparent

Fracture:

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

Habit:

Euhedral Crystals - Occurs as well-formed crystals showing good external form.

Hardness:

8 - Topaz

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Londonite

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

Optical Data:

Isotropic, n=1.693.

Calculated Properties of Londonite

Electron Density:

Bulk Density (Electron Density)=3.21 gm/cc
note: Specific Gravity of Londonite =3.34 gm/cc.

Fermion Index:

Fermion Index = 0.08
Boson Index = 0.92

Photoelectric:

PE_Londonite= 33.04 barns/electron
U=PE_Londonite x r_electron= 106.21 barns/cc.

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

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

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

References:

NAME( AmMin, Vol 87, p 356) PHYS. PROP.(AmMin, Vol 87, p 356) OPTIC PROP.(AmMin, Vol 87, p 356)

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

Search for Londonite using:

[AOL] [Bing] [Dog Pile] [GeoScienceWorld] [HotBot] [Ixquick] [Lycos] [MAMMA] [Scirus] [Teoma] [WebCrawler] [Wikipedia] [YAHOO]

Visit our Advertisers for Londonite :

A Bijoux Google Search for Londonite
Adam's Minerals Google Search for Londonite
Cape Minerals Google Search for Londonite
Dakota Matrix Minerals Google Search for Londonite
Excalibur Mineral Corp. Google Search for Londonite
Exceptional Minerals Google Search for Londonite
John Betts Fine Minerals Search for Londonite
McDougall Minerals Google Search for Londonite
Mineral News Website Link
Rock and Mineral Shows Google Search for Londonite
Weinrich Minerals, Inc. Google Search for Londonite

Ask about Londonite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

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: