Grimaldiite Mineral Data

Grimaldiite Mineral Data +

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General Grimaldiite Information

Chemical Formula:

Cr+++O(OH)

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

Empirical Formula:

CrO(OH)

IMA Status:

Approved IMA 1967

Locality:

Link to MinDat.org Location Data.

Grimaldiite Image

Images:

Grimaldiite

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

Axial Ratios:

a:c = 1:4.50454

Cell Dimensions:

a = 2.973, c = 13.392, Z = 3; V = 102.51 Den(Calc)= 4.13

Crystal System:

Trigonal - Hexagonal ScalenohedralH-M Symbol (3 2/m) Space Group: R 3m

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

By Intensity(I/I_o): 4.44(1), 2.407(0.3), 1.858(0.25),

Physical Properties of Grimaldiite

Color:

Dark red, Reddish brown.

Density:

4.11

Diaphaniety:

Opaque

Hardness:

3.5-4.5 - Between Copper Penny and Fluorite-Apatite

Luster:

Metallic

Streak:

red

Optical Properties of Grimaldiite

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

Electron Density:

r_electron=3.98 gm/cc
note: r_Grimaldiite=4.13 gm/cc.

Fermion Index

Fermion Index = 0.05829
Boson Index = 0.94171

Photoelectric:

PE_Grimaldiite= 13.79 barns/electron
U=PE_Grimaldiite x r_electron= 54.95 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Grimaldiite is Not Radioactive

Grimaldiite Classification

Dana Class:

6.1.5.1 (6)Hydroxides and Oxides Containing Hydroxyl

(6.1)where X+++O OH

(6.1.5)Dana Group

6.1.5.1 Grimaldiite CrO(OH) R 3m 3 2/m

Strunz Class:

IV/F.07-70 IV - Oxides

IV/F - Hydroxides and oxidic hydrates, water-bearing oxides with layered structure

IV/F.07 - Lithiophorite - Grimaldiite series

IV/F.07-10 Lithiophorite (Al,Li)MnO2(OH)2 R 3m 3 2/m

IV/F.07-20 Asbolane (Co,Ni)1-y(MnO2)2-x(OH)2-2y2x·n(H2O) Unk Hex

IV/F.07-30 Heterogenite-2H CoO(OH) P 6₃/mmc 6/m 2/m 2/m

IV/F.07-40 Heterogenite-3R CoO(OH) R 3m 3 2/m

IV/F.07-50 Bracewellite CrO(OH) Pbnm 2/m 2/m 2/m

IV/F.07-60 Guyanaite CrO(OH) Pnnm 2/m 2/m 2/m

IV/F.07-70 Grimaldiite CrO(OH) R 3m 3 2/m

Other Grimaldiite Information

References:

PHYS. PROP.(Enc. of Minerals,2nd ed.,1990)

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

Grimaldiite

Cr+++O(OH)
Dana No: 6.1.5.1 Strunz No: IV/F.07-70
Locality:

Notes: