Mineralogy Database

Grimaldiite Mineral Data

Search Webmineral :

General Grimaldiite Information

Help on Chemical  Formula: Chemical Formula: Cr+++O(OH)
Help on Composition: Composition: Molecular Weight = 85.00 gm
   Chromium  61.17 %  Cr   89.40 % Cr2O3
   Hydrogen   1.19 %  H    10.60 % H2O
   Oxygen    37.64 %  O
            ______        ______ 
            100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: CrO(OH)
Help on Environment: Environment: Fine-grained intergrowth with other chromium oxide-hydroxide minerals in alluvial gravels. Trimorphous with bracewellite and guyanaite.
Help on IMA Status: IMA Status: Approved IMA 1967
Help on Locality: Locality: Basin of the Merume River, Guyana. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for Frank Saverio Grimaldi (1915- ), formerly Chief Chemist, U.S. Geological Survey.
Help on Name Pronunciation: Name Pronunciation: Grimaldiite + Pronunciation Say GRIMALDIITE

Grimaldiite Image

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


Comments: Grimaldiite, variety merumite, stream rounded crystalline grains.
Location: Merume River, Mazaruni-Potaro District, Guyana. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Grimaldiite Crystallography

Help on Axial Ratios: Axial Ratios: a:c = 1:4.50454
Help on Cell Dimensions: Cell Dimensions: a = 2.973, c = 13.392, Z = 3; V = 102.51 Den(Calc)= 4.13
Help on Crystal System: Crystal System: Trigonal - Hexagonal Scalenohedral H-M Symbol (3 2/m) Space Group: R 3m
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 4.44(1), 2.407(0.3), 1.858(0.25),

Physical Properties of Grimaldiite

Help on Color: Color: Dark red, Reddish brown.
Help on Density: Density: 4.11
Help on Diaphaneity: Diaphaneity: Opaque
Help on Hardness: Hardness: 3.5-4.5 - Between Copper Penny and Fluorite-Apatite
Help on Luster: Luster: Metallic
Help on Streak: Streak: red

Optical Properties of Grimaldiite

Help on Optical Data: Optical Data: NCalc= 2.22 - from Gladstone-Dale relationship (KC = 0.2953) where Ncalc=Dcalc*KC+1
NCalc= 2.21 - from Gladstone-Dale relationship (KC = 0.2953) where Ncalc=Dmeas*KC+1

Calculated Properties of Grimaldiite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=3.98 gm/cc
note: Specific Gravity of Grimaldiite =4.13 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.05
Boson Index = 0.95
Help on Photoelectric: Photoelectric: PEGrimaldiite = 13.79 barns/electron
U=PEGrimaldiite x rElectron Density= 54.95 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Grimaldiite is Not Radioactive

Grimaldiite Classification

Help on  Dana Class: Dana Class: (06)Hydroxides and Oxides Containing Hydroxyl
  (06.01)where X+++O OH
  (06.01.05)Dana Group Grimaldiite CrO(OH) R 3m 3 2/m
Help on  Strunz Class: Strunz Class: 04.FE.20 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate
  04.F - Hydroxides (without V or U)
  04.FE -Hydroxides with OH, without H2O; sheets of edge-sharing octahedra
04.FE.20 Grimaldiite CrO(OH) R 3m 3 2/m
04.FE.20 Heterogenite-2H CoO(OH) P 63/mmc 6/m 2/m 2/m
04.FE.20 Heterogenite-3R CoO(OH) R 3m 3 2/m

Other Grimaldiite Information

Help on References: References: NAME( AntBidBlaNic3) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990)
Help on See Also: See Also: Links to other databases for Grimaldiite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info

Search for Grimaldiite using:

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

Visit our Advertisers for Grimaldiite :

Ask about Grimaldiite 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 Grimaldiite Specimen Label here :


Dana No: Strunz No: 04.FE.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.