Mineralogy Database

Cumengite Mineral Data

Search Webmineral :

General Cumengite Information

Help on Chemical  Formula: Chemical Formula: Cu20Pb21Cl42(OH)40•6H2O
Help on Composition: Composition: Molecular Weight = 7,899.52 gm
   Copper    16.09 %  Cu   20.14 % CuO
   Hydrogen   0.66 %  H     5.93 % H2O
   Lead      55.08 %  Pb   59.34 % PbO
   Chlorine  18.85 %  Cl   18.85 % Cl
               -   %   Cl   -4.25 % -O=Cl2   
   Oxygen     9.32 %  O
            ______        ______ 
            100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Cu20Pb21Cl42(OH)40•6(H2O)
Help on Environment: Environment: Oxidized zone of sedimentary copper ores associated with boleite.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1893
Help on Locality: Locality: Boleo, near Santa Rosalia, Baja California Sur. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for Edouard Cumenge (1828-1902), French mining engineer for the Boleo mines.
Help on Synonym: Synonym: Cumengeite

Cumengite Image

Click Here for Larger   Image in a New Browser Window Images:
Click Here for Larger   Image

  Cumengite   Boleite

Comments: Inky blue cumengite "sixling" epitaxially overgrown on boleite.
Location: Amelia mine, Santa Rosalia, Baja California Sur, Mexico. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Cumengite Crystallography

Help on Axial Ratios: Axial Ratios: a:c = 1:1.62204
Help on Cell Dimensions: Cell Dimensions: a = 15.1007, c = 24.494, Z = 2; V = 5,585.40 Den(Calc)= 4.70
Help on Crystal System: Crystal System: Tetragonal - Ditetragonal Dipyramidal H-M Symbol (4/m 2/m 2/m) Space Group: I 4/mmm
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.372(1), 4.83(0.9), 2.657(0.8),

Physical Properties of Cumengite

Help on Cleavage: Cleavage: {101} Distinct, {110} Poor
Help on Color: Color: Indigo blue.
Help on Density: Density: 4.67
Help on Diaphaneity: Diaphaneity: Transparent
Help on Fracture: Fracture: Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.
Help on Habit: Habit: Epitaxial - Crystallographic alignment with a precursor mineral
Help on Habit: Habit: Pseudo Cubic - Crystals show a cubic outline.
Help on Hardness: Hardness: 2.5 - Finger Nail
Help on Luster: Luster: Adamantine
Help on Streak: Streak: blue

Optical Properties of Cumengite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= -0.092 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.085 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2093,KPDmeas= 0.2106,KC= 0.1929
Ncalc = 1.9 - 1.91
Help on Optical Data: Optical Data: Uniaxial (-), e=1.926, w=2.041, bire=0.1150.

Calculated Properties of Cumengite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=4.09 gm/cc
note: Specific Gravity of Cumengite =4.70 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.12
Boson Index = 0.88
Help on Photoelectric: Photoelectric: PECumengite = 981.17 barns/electron
U=PECumengite x rElectron Density=4,011.66 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Cumengite is Not Radioactive

Cumengite Classification

Help on  Dana Class: Dana Class: (10)Oxyhalides and Hydroxyhalides
  (10.06)where Am Bn (O,OH)p Xq
  (10.06.07)Dana Group Cumengite Cu20Pb21Cl42(OH)40•6H2O I 4/mmm 4/m 2/m 2/m
Help on  Strunz Class: Strunz Class: 03.DB.20 03 - HALIDES
  03.D - Oxyhalides, Hydroxyhalides and Related Double Halides
  03.DB -With Pb, Cu, etc.
03.DB.20 Cumengite Cu20Pb21Cl42(OH)40•6H2O I 4/mmm 4/m 2/m 2/m

Other Cumengite Information

Help on References: References: NAME( Ford32) PHYS. PROP.(Dana8, AmMin v91, p1208) OPTIC PROP.(Ford32)
Help on See Also: See Also: Links to other databases for Cumengite :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - EUROmin Project
5 - Ecole des Mines de Paris
6 - GeoScienceWorld
7 - Google Images
8 - Google Scholar
9 - MinDAT
10 - Mineralienatlas (Deutsch)
11 - Online Mineral Museum
12 - QUT Mineral Atlas
13 - Ruff.Info

Search for Cumengite using:

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

Visit our Advertisers for Cumengite :

Ask about Cumengite 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 Espaņol

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


Dana No: Strunz No: 03.DB.20





Dakota Matrix
Excalibur Minerals
Exceptional Minerals
Hudson Insitute
John Betts Fine Minerals
Mc Dougall Minerals
Mineral News
Rock and Mineral Shows
Weinrich Minerals, Inc.