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Grandreefite
A valid IMA mineral species
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About Grandreefite
View of the Grand Reef looking up Laurel Creek
Grand Reef Mine, Laurel Canyon, Grand Reef Mountain, Klondyke, Aravaipa Mining District, Graham County, Arizona, USA
Grand Reef Mine, Laurel Canyon, Grand Reef Mountain, Klondyke, Aravaipa Mining District, Graham County, Arizona, USA
Formula:
Pb2(SO4)F2
Colour:
Colourless
Lustre:
Sub-Adamantine
Hardness:
2½
Specific Gravity:
7.0
Crystal System:
Monoclinic
Name:
Named by Anthony R. Kampf, Peter J. Dunn, and Eugene E. Foord in 1989 after the type locality of Grand Reef Mine, Arizona.
A rare secondary lead sulphate fluoride.
Structurally related to Unnamed (Ba Thiosulphate Fluoride).
The higher indices of refraction, smaller 2V, and weaker dispersion are useful in distinguishing grandreefite from pseudograndreefite.
Structurally related to Unnamed (Ba Thiosulphate Fluoride).
The higher indices of refraction, smaller 2V, and weaker dispersion are useful in distinguishing grandreefite from pseudograndreefite.
Unique Identifiers
Mindat ID:
1738
Long-form identifier:
mindat:1:1:1738:7
IMA Classification of Grandreefite
Approved
IMA Formula:
Pb2+2(S6+O4)F2
Approval year:
1988
First published:
1989
Classification of Grandreefite
7.BD.45
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
B : Sulfates (selenates, etc.) with additional anions, without H2O
D : With only large cations
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
B : Sulfates (selenates, etc.) with additional anions, without H2O
D : With only large cations
12.1.2.1
12 : COMPOUND HALIDES
1 : Miscellaneous
12 : COMPOUND HALIDES
1 : Miscellaneous
26.22
26 : Sulphates with Halide
26 : Sulphates with Halide
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 for Standard |
|---|---|---|
| Grf | 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 Grandreefite
Sub-Adamantine
Transparency:
Transparent
Colour:
Colourless
Streak:
White
Hardness:
2½ on Mohs scale
Tenacity:
Brittle
Cleavage:
None Observed
Fracture:
Conchoidal
Density:
7.0(1) g/cm3 (Measured) 7.15 g/cm3 (Calculated)
Comment:
Measured with Berman balance using 3.43 mg of sample.
Optical Data of Grandreefite
Type:
Biaxial (+)
RI values:
nα = 1.872 nβ = 1.873 nγ = 1.897
2V:
Measured: 23° , Calculated: 24°
Max. Birefringence:
δ = 0.025
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
very strong
Optical Extinction:
X = c, Y = a, Z = b.
Chemistry of Grandreefite
Mindat Formula:
Pb2(SO4)F2
Element Weights:
Elements listed:
Crystallography of Grandreefite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/b
Setting:
A2/a
Cell Parameters:
a = 8.667(1) Å, b = 4.4419(6) Å, c = 14.242(2) Å
β = 107.418(2)°
β = 107.418(2)°
Ratio:
a:b:c = 1.951 : 1 : 3.206
Unit Cell V:
523.15 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Prismatic and striated parallel to [001]. The forms {l20}, {l30}, {293}, {2-93}, and {l01} were present.
Twinning:
Coarse polysynthetic twins of undetermined law observed only in transmitted light under crossed polars.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
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) |
|---|---|---|---|---|---|---|---|
| 0001350 | Grandreefite | Kampf A R (1991) Grandreefite, Pb2F2SO4: Crystal structure and relationship to the lanthanide oxide sulfates, Ln2O2SO4 American Mineralogist 76 278-282 |  | 1991 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.159 Å | (100) |
| 3.116 Å | (90) |
| 3.084 Å | (80) |
| 2.281 Å | (50) |
| 1.824 Å | (50) |
| 1.806 Å | (60) |
| 1.370 Å | (50b) |
Comments:
Grand Reef mine, Arizona, USA. Data from the type description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47b : [Sulfates and sulfites] | |
| 47g : [Halogen-bearing surface weathering minerals] |
Type Occurrence of Grandreefite
General Appearance of Type Material:
Isolated prismatic crystals
Place of Conservation of Type Material:
Natural History Museum, Los Angeles, California, USA, 33608.
National Museum of Natural History, Washington, D.C., USA, 166055.
National Museum of Natural History, Washington, D.C., USA, 166055.
Geological Setting of Type Material:
Epithermal lead-copper-silver deposit, which is hosted by a silicified breccia.
Associated Minerals at Type Locality:
Synonyms of Grandreefite
Other Language Names for Grandreefite
Common Associates
Associations Based on Photo Data:
| 1 photo of Grandreefite associated with Pseudograndreefite | Pb6(SO4)F10 |
Related Minerals - Strunz-mindat Grouping
| 7.BD. | Hasanovite | KNa(MoO2)(SO4)2 |
| 7.BD. | Kennygayite | [Pb4O2(OH)2](SO4) |
| 7.BD. | Adanite | Pb2(Te4+O3)(SO4) |
| 7.BD. | Cadsulfohite | Cd2(SO4)(OH)2 |
| 7.BD. | Hyblerite | Pb4Bi2(SO4)2(CO3)O4 |
| 7.BD. | Zanelliite | PbCu9[AsO3.5(OH)0.5]2(AsO4)2(OH)9(H2O)3 |
| 7.BD. | Evanichite | Pb6Cr3+(Cr6+O4)2(SO4)(OH)7FCl |
| 7.BD.05 | Sulphohalite | Na6(SO4)2FCl |
| 7.BD.10 | Galeite | Na15(SO4)5F4Cl |
| 7.BD.10 | Schairerite | Na21(SO4)7ClF6 |
| 7.BD.15 | Kogarkoite | Na3(SO4)F |
| 7.BD.20 | Aiolosite | Na4Bi(SO4)3Cl |
| 7.BD.20 | Caracolite | Na3Pb2(SO4)3Cl |
| 7.BD.20 | Cesanite | Na3Ca2(SO4)3(OH) |
| 7.BD.25 | Burkeite | Na6(CO3)(SO4)2 |
| 7.BD.30 | Hanksite | Na22K(SO4)9(CO3)2Cl |
| 7.BD.35 | Cannonite | Bi2(SO4)O(OH)2 |
| 7.BD.40 | Lanarkite | Pb2(SO4)O |
| 7.BD.50 | Itoite | Pb3Ge4+(SO4)2O2(OH)2 |
| 7.BD.55 | Chiluite | Bi3Te6+Mo6+O10.5 |
| 7.BD.60 | Hectorfloresite | Na9(SO4)4(IO3) |
| 7.BD.65 | Pseudograndreefite | Pb6(SO4)F10 |
| 7.BD.70 | Sundiusite | Pb10(SO4)O8Cl2 |
Fluorescence of Grandreefite
None observed.
Other Information
Notes:
Decomposes in cold water.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Grandreefite
mindat.org URL:
https://www.mindat.org/min-1738.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Grandreefite
Reference List:
Kampf, Anthony R., Dunn, Pete J., Foord, Eugene E. (1989) Grandreefite, pseudograndreefite, laurelite, and aravaipaite: Four new minerals from the Grand Reef mine, Graham County, Arizona. American Mineralogist, 74 (7-8) 927-933
Localities for Grandreefite
Showing 3 localities.
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.
Greece | |
| lavrion.gr (2026) |
| Wendel et al. (1999) |
USA (TL) | |
| Kampf et al. (1989) +2 other references |
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Grand Reef Mine, Laurel Canyon, Grand Reef Mountain, Klondyke, Aravaipa Mining District, Graham County, Arizona, USA