Fencooperite
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About Fencooperite
Formula:
Ba6Fe3+3Si8O23(CO3)2Cl3 · H2O
Colour:
Black
Lustre:
Adamantine, Vitreous
Hardness:
4½ - 5
Crystal System:
Trigonal
Name:
Named for California mineral collector Joseph Fenimore Cooper, Jr. (April 30, 1937, Santa Cruz, California - June 6, 2017, Santa Cruz, California). He was an avid collector of western U.S. minerals, especially in California and Nevada, and contributed to more than twenty publications.
This page provides mineralogical data about Fencooperite.
Classification of Fencooperite
Approved
Approval year:
2000
8/C.37-10
9.BH.20
9 : SILICATES (Germanates)
B : Sorosilicates
H : Sorosilicates with Si3O10, Si4O11, etc. anions; cations in tetrahedral [4] and greater coordination
9 : SILICATES (Germanates)
B : Sorosilicates
H : Sorosilicates with Si3O10, Si4O11, etc. anions; cations in tetrahedral [4] and greater coordination
Physical Properties of Fencooperite
Optical Data of Fencooperite
Type:
Uniaxial (-)
RI values:
nω = 1.723 nε = 1.711
Max Birefringence:
δ = 0.012

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:
High
Pleochroism:
Strong
Comments:
nω = deep bluish-black
nε = light greenish-gray
nε = light greenish-gray
Chemical Properties of Fencooperite
Formula:
Ba6Fe3+3Si8O23(CO3)2Cl3 · H2O
Crystallography of Fencooperite
Crystal System:
Trigonal
Class (H-M):
3m - Ditrigonal Pyramidal
Space Group:
P3m1
Cell Parameters:
a = 10.727 Å, c = 7.085 Å
Ratio:
a:c = 1 : 0.66
Unit Cell V:
706.1 ų
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) |
---|---|---|---|---|---|---|---|
0005724 | Fencooperite | Grice J D (2001) The crystal structure of fencooperite: Unique [Fe3O13] pinwheels cross-connected by [Si8O22] islands The Canadian Mineralogist 39 1065-1071 | ![]() | 2001 | 0 | 293 |
CIF Raw Data - click here to close
Type Occurrence of Fencooperite
Place of Conservation of Type Material:
National Mineral Collection at the Geological Survey of Canada, Ottawa.
Synonyms of Fencooperite
Other Language Names for Fencooperite
German:Fencooperit
Russian:Фенкуперит
Simplified Chinese:氯碳硅铁钡石
Spanish:Fencooperita
Traditional Chinese:氯碳矽鐵鋇石
Common Associates
Associated Minerals Based on Photo Data:
1 photo of Fencooperite associated with Sanbornite | Ba2(Si4O10) |
Related Minerals - Nickel-Strunz Grouping
9.BH. | Bunnoite | Mn2+6AlSi6O18(OH)3 | Tric. 1 : P1 |
9.BH.05 | Aminoffite | Ca2(Be,Al)(Si2O7)(H2O,OH) | Tet. |
9.BH.10 | Kinoite | Ca2Cu2(H2O)2[Si3O10] | Mon. 2/m : P21/m |
9.BH.15 | Akatoreite | Mn2+9Al2Si8O24(OH)8 | Tric. |
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.
References for Fencooperite
Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Roberts, A.C., Grice, J.D., Dunning, G.E., and Venance, K.E. (2001) Fencooperite, Ba6Fe33+Si8O23(CO3)2Cl3·H2O, a new mineral species from Trumbull Peak, Mariposa County, California. Canadian Mineralogist: 39: 1059–1064.
Grice, J.D. (2001) The crystal structure of fencooperite: Unique [Fe33+O13] pinwheels cross-connected by [Si8O22] islands. Canadian Mineralogist: 39: 1065-1071.
Jambor, J.L. and Roberts, A.C. (2002) New mineral names. American Mineralogist: 87: 765-768.
Internet Links for Fencooperite
mindat.org URL:
https://www.mindat.org/min-10343.html
Please feel free to link to this page.
Please feel free to link to this page.
External Links:
Mineral Dealers:
Localities for Fencooperite
Locality List




All localities listed without proper references should be considered as questionable.
USA | |
| Grice, J.D. (2001) The crystal structure of fencooperite: Unique [Fe33+O13] pinwheels cross-connected by [Si8O22] islands. Canadian Mineralogist: 39: 1065-1071.; Jambor, J.L. and Roberts, A.C. (2002) New mineral names. American Mineralogist: 87: 765-768. |
| Roberts, A.C., Grice, J.D., Dunning, G.E., and Venance, K.E. (2001) Fencooperite, Ba6Fe33+Si8O23(CO3)2Cl3·H2O, a new mineral species from Trumbull Peak, Mariposa County, California. Canadian Mineralogist: 39: 1059–1064.; Jambor, J.L. and Roberts, A.C. (2002) New mineral names. American Mineralogist: 87: 765-768. |
Trumbull Peak Ba-silicate deposit, Trumbull Peak, Clearing House, Clearing House Mining District, East Belt, Mariposa Co., California, USA