Grimaldiite
A valid IMA mineral species
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About Grimaldiite
Formula:
CrO(OH)
may rather be HCrO2 due to relations with delafossite
Colour:
Deep red to pinkish brown
Lustre:
Sub-Metallic
Hardness:
3½ - 4½
Specific Gravity:
4.11 - 4.12
Crystal System:
Trigonal
Name:
Named in 1967 by Charles Milton, Daniel E. Appleman, Edward Ching-Te Chao, Frank Cuttita, Joseph I. Dinnin, Edward J. Dwornik, Margaret Hall, Blanche L. Ingram, and Harry J. Rose, Jr. in honor of Frank Saverio Grimaldi [October 11, 1915 - April 30, 1985, Vienna, Virginia, USA], former chief chemist of the U. S. Geological Survey.
Polymorph of:
As with other Cr mineral species from the Merume River locality, such as bracewellite, guyanaite, and mcconnellite this species is NOT universally present in every specimen and verification of each specimen is required.
The structure may rather be related to that of delafossite and thus the formula may be changed.
The structure may rather be related to that of delafossite and thus the formula may be changed.
Unique Identifiers
Mindat ID:
1750
Long-form identifier:
mindat:1:1:1750:9
GUID
(UUID V4):
(UUID V4):
28a18025-570c-4765-b13b-665a3f3ee9f1
IMA Classification of Grimaldiite
Approved
Classification of Grimaldiite
4.FE.20
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
E : Hydroxides with OH, without H2O; sheets of edge-sharing octahedra
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
E : Hydroxides with OH, without H2O; sheets of edge-sharing octahedra
6.1.5.1
6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
1 : XO(OH)
6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
1 : XO(OH)
7.14.3
7 : Oxides and Hydroxides
14 : Oxides of Cr
7 : Oxides and Hydroxides
14 : Oxides of Cr
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference |
|---|---|---|
| Gmd | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Grimaldiite
Sub-Metallic
Transparency:
Transparent, Translucent
Colour:
Deep red to pinkish brown
Hardness:
3½ - 4½ on Mohs scale
Cleavage:
Distinct/Good
{0001}
{0001}
Density:
4.11 - 4.12 g/cm3 (Measured) 4.13 g/cm3 (Calculated)
Comment:
synthetic
Optical Data of Grimaldiite
Type:
Uniaxial
RI values:
nω = 2.155 nε = 1.975
Max Birefringence:
δ = 0.180
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Very High
Comments:
n = ∼2.05, varies in mixtures
Chemistry of Grimaldiite
Mindat Formula:
CrO(OH)
may rather be HCrO2 due to relations with delafossite
may rather be HCrO2 due to relations with delafossite
Elements listed:
Crystallography of Grimaldiite
Crystal System:
Trigonal
Class (H-M):
3m - Ditrigonal Pyramidal
Space Group:
R3m
Cell Parameters:
a = 2.973(2) Å, c = 13.392(1) Å
Ratio:
a:c = 1 : 4.505
Unit Cell V:
102.51 ų (Calculated from Unit Cell)
Z:
3
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0013343 | Grimaldiite | Christensen A N, Hansen P, Lehmann M S (1977) Isotope effects in the bonds of alpha-CrOOH and alpha-CrOOD Journal of Solid State Chemistry 21 325-329 | 1977 | synthetic | 0 | 293 | |
| 0013344 | Grimaldiite | Christensen A N, Hansen P, Lehmann M S (1977) Isotope effects in the bonds of alpha-CrOOH and alpha-CrOOD Journal of Solid State Chemistry 21 325-329 | 1977 | synthetic | 0 | 293 | |
| 0013345 | Grimaldiite | Christensen A N, Hansen P, Lehmann M S (1977) Isotope effects in the bonds of alpha-CrOOH and alpha-CrOOD Journal of Solid State Chemistry 21 325-329 | 1977 | synthetic | 0 | 293 | |
| 0013346 | Grimaldiite | Christensen A N, Hansen P, Lehmann M S (1977) Isotope effects in the bonds of alpha-CrOOH and alpha-CrOOD Journal of Solid State Chemistry 21 325-329 | 1977 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 4.47 Å | (vvs) |
| 2.401 Å | (vs) |
| 1.857 Å | (vs) |
| 1.486 Å | (ms) |
| 1.537 Å | (mw) |
| 2.528 Å | (w) |
| 1.409 Å | (w) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-𝑇 alteration and/or metamorphism | |
| 33 : Minerals deposited by hydrothermal metal-rich fluids (see also [#12]) | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47h : [Near-surface oxidized, dehydrated minerals] |
Type Occurrence of Grimaldiite
Place of Conservation of Type Material:
Harvard University, Cambridge, Massachusetts, USA; The Natural History Museum, London, England, 1979,136.
Geological Setting of Type Material:
Alluvial gravels
Associated Minerals at Type Locality:
Reference:
Milton C, Appleman D E, Appleman M H, Chao E C T, Cuttita F, Dinnin J I, Dwornik E J, Ingram B L, Rose H J (1976) Merumite, a complex assemblage of chromium minerals from Guyana. U.S. Geological Survey Professional Paper 887, 1-29
Synonyms of Grimaldiite
Other Language Names for Grimaldiite
Common Associates
Associated Minerals Based on Photo Data:
| 8 photos of Grimaldiite associated with Crocoite | PbCr6+O4 |
| 3 photos of Grimaldiite associated with Mcconnellite | CuCrO2 |
| 3 photos of Grimaldiite associated with Philipsbornite | PbAl3(AsO4)(AsO3OH)(OH)6 |
| 2 photos of Grimaldiite associated with Petterdite | PbCr3+2(CO3)2(OH)4 · H2O |
| 1 photo of Grimaldiite associated with Guyanaite | CrO(OH) |
| 1 photo of Grimaldiite associated with Bracewellite | CrO(OH) |
| 1 photo of Grimaldiite associated with Gold | Au |
| 1 photo of Grimaldiite associated with Cerussite | PbCO3 |
| 1 photo of Grimaldiite associated with Galena | PbS |
Related Minerals - Strunz-mindat Grouping
| 4.FE.05 | Amakinite | Fe2+(OH)2 |
| 4.FE.05 | Brucite | Mg(OH)2 |
| 4.FE.05 | Portlandite | Ca(OH)2 |
| 4.FE.05 | Pyrochroite | Mn(OH)2 |
| 4.FE.05 | Theophrastite | Ni(OH)2 |
| 4.FE.10 | Bayerite | Al(OH)3 |
| 4.FE.10 | Doyleite | Al(OH)3 |
| 4.FE.10 | Gibbsite | Al(OH)3 |
| 4.FE.10 | Nordstrandite | Al(OH)3 |
| 4.FE.15 | Böhmite | AlO(OH) |
| 4.FE.15 | Lepidocrocite | γ-Fe3+O(OH) |
| 4.FE.20 | Heterogenite | Co3+O(OH) |
| 4.FE.25 | Feitknechtite | Mn3+O(OH) |
| 4.FE.25 | Lithiophorite | (Al,Li)MnO2(OH)2 |
| 4.FE.30 | Quenselite | PbMnO2(OH) |
| 4.FE.35 | Ferrihydrite | Fe3+10O14(OH)2 |
| 4.FE.40 | Feroxyhyte | Fe3+O(OH) |
| 4.FE.40 | Vernadite | (Mn4+,Fe3+,Ca,Na)(O,OH)2 · nH2O |
| 4.FE.45 | Quetzalcoatlite | Zn6Cu3(TeO6)2(OH)6 · AgxPbyClx+2y |
| 4.FE.50 | Fuettererite | Pb3Cu2+6Te6+O6(OH)7Cl5 |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:
Found in some processing wastes of chromite mills in India.
Internet Links for Grimaldiite
mindat.org URL:
https://www.mindat.org/min-1750.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
References for Grimaldiite
Reference List:
Localities for Grimaldiite
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Australia | |
| Bottrill +1 other reference |
Bolivia | |
| Livingstone et al. (1984) |
| Livingstone et al. (1984) +1 other reference |
Canada | |
| Robichaud et al. (2011) |
China | |
| Bingxi Wang (1983) |
Guyana (TL) | |
| Geol.Soc.Amer. (1967) +1 other reference |
Russia | |
| Суставов et al. (2012) |
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Red Lead Mine, Dundas mineral field, Zeehan mining district, West Coast municipality, Tasmania, Australia