Fuenzalidaite
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About Fuenzalidaite
Formula:
K6(Na,K)4Na6Mg10(SO4)12(IO3)12 · 12H2O
Colour:
Colourless to pale yellow
Lustre:
Vitreous
Hardness:
2 - 3
Crystal System:
Trigonal
Name:
Named by Judith A. Konnert, Howard T. Evans, Jr., James J. McGee, and George E. Ericksen in 1994 in honor of Humberto Fuenzalida Villegas (27 March 1904, Curicó, Chile - 24 February 1966, Santiago, Chile), geographer, geologist, paleontologist, academic and naturalist. He was director of the National Museum of Natural History between 1948 and 1964. He founded the Chilean School of Geology within the Faculty of Physical Sciences and Mathematics at the University of Chile (and was the first Director) and the Institute of Geography at the Faculty of Education at the same university. He also co-founded the Antarctic Institute of Chile (INACH) and the Geological Society of Chile.
Isostructural with:
Carlosruizite-Fuenzalidaite Series. The S analogue of carlosruizite.
Occurs in veins and veinlets of the white nitrate ore ("Caliche Blanco").
The structure is based on two complex slabs, normal to the c axis; each slab consists of a double layer formed by trigonal-pyramidal iodate groups, bounded at the top and bottom by layers of SO4 groups. The layers are separated by K, with Na and Mg helding the layer complex together. The structure somewhat resembles that of alunite group members.
Occurs in veins and veinlets of the white nitrate ore ("Caliche Blanco").
The structure is based on two complex slabs, normal to the c axis; each slab consists of a double layer formed by trigonal-pyramidal iodate groups, bounded at the top and bottom by layers of SO4 groups. The layers are separated by K, with Na and Mg helding the layer complex together. The structure somewhat resembles that of alunite group members.
Classification of Fuenzalidaite
Approved
First Published:
1994
6/D.16-50
7.DG.40
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
G : With large and medium-sized cations; with NO3, CO3, B(OH)4, SiO4 or IO3
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
G : With large and medium-sized cations; with NO3, CO3, B(OH)4, SiO4 or IO3
Dana 7th ed.:
23.1.2.1
23.1.2.1
23 : COMPOUND IODATES
1 : Miscellaneous
23 : COMPOUND IODATES
1 : Miscellaneous
Physical Properties of Fuenzalidaite
Vitreous
Transparency:
Transparent
Colour:
Colourless to pale yellow
Hardness:
2 - 3 on Mohs scale
Tenacity:
Brittle
Optical Data of Fuenzalidaite
Type:
Uniaxial (-)
RI values:
nω = 1.622 nε = 1.615
Max Birefringence:
δ = 0.007

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:
Moderate
Chemical Properties of Fuenzalidaite
Formula:
K6(Na,K)4Na6Mg10(SO4)12(IO3)12 · 12H2O
IMA Formula:
K3Na5Mg5(IO3)6(SO4)6 · 6H2O
Crystallography of Fuenzalidaite
Crystal System:
Trigonal
Class (H-M):
3m (3 2/m) - Hexagonal Scalenohedral
Space Group:
P3c1
Cell Parameters:
a = 9.4643(4) Å, c = 27.336(6) Å
Ratio:
a:c = 1 : 2.888
Unit Cell V:
2,120.52 ų (Calculated from Unit Cell)
X-Ray Powder Diffraction
Powder Diffraction Data:
d-spacing | Intensity |
---|---|
13.67 | (50) |
7.05 | (40) |
3.927 | (100) |
3.023 | (41) |
2.681 | (33) |
Type Occurrence of Fuenzalidaite
General Appearance of Type Material:
thin, euhedral, platy crystals with hexagonal outline, usually less than 200 microns in diameter and 20 microns thick
Geological Setting of Type Material:
veins and veinlets of "caliche blanco"
Associated Minerals at Type Locality:
Synonyms of Fuenzalidaite
Other Language Names for Fuenzalidaite
Relationship of Fuenzalidaite to other Species
Forms a series with:
Common Associates
Associated Minerals Based on Photo Data:
Related Minerals - Nickel-Strunz Grouping
7.DG.05 | Darapskite | Na3(SO4)(NO3) · H2O | Mon. 2/m |
7.DG.10 | Clinoungemachite | (Na, K, Fe, SO4) | Mon. 2/m |
7.DG.10 | Humberstonite | Na7K3Mg2(SO4)6(NO3)2 · 6H2O | Trig. 3 : R3 |
7.DG.10 | Ungemachite | K3Na8Fe(SO4)6(NO3)2 · 6H2O | Trig. 3 : R3 |
7.DG.15 | Bentorite | Ca6(Cr3+,Al)2(SO4)3(OH)12 · 26H2O | Hex. 6/mmm (6/m 2/m 2/m) : P63/mmc |
7.DG.15 | Charlesite | Ca6(Al,Si)2(SO4)2[B(OH)4](OH,O)12 · 26H2O | Trig. 3m : P3 1c |
7.DG.15 | Ettringite | Ca6Al2(SO4)3(OH)12 · 26H2O | Trig. 3m : P3 1c |
7.DG.15 | Jouravskite | Ca3Mn4+(SO4)(CO3)(OH)6 · 12H2O | Hex. |
7.DG.15 | Sturmanite | Ca6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2O | Trig. 3m : P3 1c |
7.DG.15 | Thaumasite | Ca3(SO4)[Si(OH)6](CO3) · 12H2O | Hex. 6 : P63 |
7.DG.15 | Carraraite | Ca3(SO4)[Ge(OH)6](CO3) · 12H2O | Hex. |
7.DG.15 | Buryatite | Ca3(Si,Fe,Al)(SO4)[B(OH)4]O(OH)5 · 12H2O | |
7.DG.20 | Rapidcreekite | Ca2(SO4)(CO3) · 4H2O | Orth. |
7.DG.20 | Korkinoite | Ca4(SO4)2(CO3)2 · 9(H2O) | Orth. mmm (2/m 2/m 2/m) : Pmmm |
7.DG.25 | Tatarskite | Ca6Mg2(SO4)2(CO3)2(OH)4Cl4 · 7H2O | Orth. |
7.DG.30 | Nakauriite | Cu8(SO4)4(CO3)(OH)6 · 48H2O | Orth. |
7.DG.35 | Chessexite | (Na,K)4Ca2(Mg,Zn)3Al8(SO4)10(SiO4)2 · 40H2O | Orth. |
7.DG.40 | Carlosruizite | K6(Na,K)4Na6Mg10(SeO4)12(IO3)12 · 12H2O | Trig. 3m (3 2/m) : P3c1 |
7.DG.45 | Chelyabinskite | (Ca,Mg)3(SO4,CO3)2[Si(OH)6] · 9H2O (?) | Orth. |
Related Minerals - Dana Grouping (8th Ed.)
23.1.2.2 | Carlosruizite | K6(Na,K)4Na6Mg10(SeO4)12(IO3)12 · 12H2O | Trig. 3m (3 2/m) : P3c1 |
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 Fuenzalidaite
Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Konnert, J.A., Evans, H.T.Jr., McGee, J.J., Ericksen, G.E. (1994) Mineralogical studies of the nitrate deposits of Chile: VII. Two new saline minerals with the composition K6(Na,K)4Na6Mg10(XO4)12(IO3)12.l2H2O: Fuenzalidaite (X = S) and carlosruizite (X = Se). American Mineralogist: 79: 1003-1008.
Mandarino, J.A. (1996) Abstracts of New Mineral Descriptions. Mineralogical Record: 27: 202-203.
Mandarino J.A. (1997) New Minerals 1990-1994. The Mineralogical Record Inc.
Internet Links for Fuenzalidaite
mindat.org URL:
https://www.mindat.org/min-1618.html
Please feel free to link to this page.
Please feel free to link to this page.
External Links:
Mineral Dealers:
Localities for Fuenzalidaite
Locality List




All localities listed without proper references should be considered as questionable.
Chile (TL) | |
| NM 90-94 (1997) |
| Pueyo, J. J., Chong, G. & Vega, M. (1998): Mineralogy and parental brine evolution in the Pedro de Valdivia nitrate deposit, Antofagasta, Chile. Revista Geologica de Chile 25, 3-15. (in Spanish) |
| collected by Reynaldo Contreira |
Personally collected by Reynaldo Contreira in 2006 |
Oficina Santa Luisa, Canchas, Antofagasta Province, Antofagasta, Chile