Jeffbenite
A valid IMA mineral species
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Formula:
Mg3Al2Si3O12
Colour:
Deep emerald green
Lustre:
Vitreous
Hardness:
7
Specific Gravity:
3.576 (Calculated)
Crystal System:
Tetragonal
Name:
Jeffbenite is named in honour of two scientists, Jeffrey W. Harris (School of Geographical and Earth Sciences, University of Glasgow, UK; b. 1940) and Ben Harte (School of Geosciences, University of Edinburgh, UK; b. 1941), whose work on diamonds, and super-deep diamonds in particular, has shaped our understanding of mantle geochemical processes for years to come.
Type Locality:
Dimorph of:
Isostructural with:
High-pressure polymorph of pyrope.
New structure type.
The petrological importance of jeffbenite is related to its very deep origin, which may allow its use as a pressure marker for detecting super-deep diamonds. Previous experimental work carried out on a Ti-rich jeffbenite establishes that it can be formed at 13 GPa and 1700 K as maximum P-T conditions.
Previously known as TAPP (Tetragonal Almandine-Pyrope Phase).
New structure type.
The petrological importance of jeffbenite is related to its very deep origin, which may allow its use as a pressure marker for detecting super-deep diamonds. Previous experimental work carried out on a Ti-rich jeffbenite establishes that it can be formed at 13 GPa and 1700 K as maximum P-T conditions.
Previously known as TAPP (Tetragonal Almandine-Pyrope Phase).
Unique Identifiers
Mindat ID:
46574
Long-form identifier:
mindat:1:1:46574:4
GUID
(UUID V4):
(UUID V4):
d6dce488-72e9-489a-9678-dbcb5faa2493
IMA Classification of Jeffbenite
Classification of Jeffbenite
9.AD.55
9 : SILICATES (Germanates)
A : Nesosilicates
D : Nesosilicates without additional anions; cations in [6] and/or greater coordination
9 : SILICATES (Germanates)
A : Nesosilicates
D : Nesosilicates without additional anions; cations in [6] and/or greater coordination
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 |
---|---|---|
Jef | 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 Jeffbenite
Vitreous
Transparency:
Transparent
Colour:
Deep emerald green
Hardness:
7 on Mohs scale
Hardness:
VHN100= 1346 - Vickers
Tenacity:
Brittle
Cleavage:
None Observed
Fracture:
Irregular/Uneven
Density:
3.576 g/cm3 (Calculated)
Optical Data of Jeffbenite
Type:
Uniaxial (-)
RI values:
nω = 1.733(5) nε = 1.721(5)
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:
Visible
Comments:
ε = light blue and ω = colourless
Chemistry of Jeffbenite
Mindat Formula:
Mg3Al2Si3O12
Elements listed:
Common Impurities:
Fe(II),Cr
Crystallography of Jeffbenite
Crystal System:
Tetragonal
Class (H-M):
4 2m - Scalenohedral
Space Group:
I4 2d
Cell Parameters:
a = 6.5231(1) Å, c = 18.1756(3) Å
Ratio:
a:c = 1 : 2.786
Unit Cell V:
773.39 ų (Calculated from Unit Cell)
Z:
4
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) |
---|---|---|---|---|---|---|---|
0002596 | Jeffbenite | Finger L W, Conrad P G (2000) The crystal structure of "Tetragonal Almandine-Pyrope Phase" (TAPP): A reexamination American Mineralogist 85 1804-1807 | 2000 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
d-spacing | Intensity |
---|---|
3.069 Å | (11) |
2.881 Å | (24) |
2.647 Å | (100) |
2.220 Å | (19) |
2.056 Å | (11) |
1.625 Å | (44) |
1.390 Å | (13) |
1.372 Å | (11) |
Comments:
From Type Description.
Geological Environment
Paragenetic Mode(s):
Paragenetic Mode | Earliest Age (Ga) |
---|---|
Stage 4b: Highly evolved igneous rocks | >3.0 |
36 : Carbonatites, kimberlites, and related igneous rocks |
Type Occurrence of Jeffbenite
Place of Conservation of Type Material:
Type material is deposited in the collections of the Museum of Mineralogy of the University of Padova, Padova, Italy, catalogue number MMP M12660
Geological Setting of Type Material:
As inclusions inside the so called "super deep diamonds" from São Luiz river alluvials, Brazil
Associated Minerals at Type Locality:
Synonyms of Jeffbenite
Related Minerals - Strunz-mindat Grouping
9.AD. | Adrianite | Ca12(Al4Mg3Si7)O32Cl6 |
9.AD.05 | Larnite | Ca2SiO4 |
9.AD.10 | Calcio-olivine | Ca2SiO4 |
9.AD.15 | Merwinite | Ca3Mg(SiO4)2 |
9.AD.20 | Bredigite | Ca7Mg(SiO4)4 |
9.AD.25 | Andradite | Ca3Fe3+2(SiO4)3 |
9.AD.25 | Almandine | Fe2+3Al2(SiO4)3 |
9.AD.25 | Calderite | Mn2+3Fe3+2(SiO4)3 |
9.AD.25 | Goldmanite | Ca3V3+2(SiO4)3 |
9.AD.25 | Grossular | Ca3Al2(SiO4)3 |
9.AD.25 | Henritermierite | Ca3Mn3+2(SiO4)2[◻(OH)4] |
9.AD.25 | Kimzeyite | Ca3Zr2(SiO4)(AlO4)2 |
9.AD.25 | Knorringite | Mg3Cr2(SiO4)3 |
9.AD.25 | Majorite | Mg3(MgSi)(SiO4)3 |
9.AD.25 | Morimotoite | Ca3(TiFe2+)(SiO4)3 |
9.AD.25 | Pyrope | Mg3Al2(SiO4)3 |
9.AD.25 | Schorlomite | Ca3Ti2(SiO4)(Fe3+O4)2 |
9.AD.25 | Spessartine | Mn2+3Al2(SiO4)3 |
9.AD.25 | Uvarovite | Ca3Cr2(SiO4)3 |
9.AD.25 | Wadalite | (Ca,Mg)6(Al,Fe3+)4((Si,Al)O4)3O4Cl3 |
9.AD.25 va | Hydrougrandite | (Ca,Mg,Fe2+)3(Fe3+,Al)2[(OH)4(SiO4)2] |
9.AD.25 va | Yamatoite | (Mn2+,Ca)3(V3+,Al)2(SiO4)3 |
9.AD.25 | Holtstamite | Ca3Al2(SiO4)2[◻(OH)4] |
9.AD.25 | Khoharite | Mg3Fe3+2(SiO4)3 |
9.AD.25 | Kerimasite | Ca3Zr2(SiO4)(Fe3+O4)2 |
9.AD.25 | Toturite | Ca3Sn2(SiO4)(Fe3+O4)2 |
9.AD.25 | Momoiite | Mn2+3V3+2(SiO4)3 |
9.AD.25 | Eringaite | Ca3Sc2(SiO4)3 |
9.AD.25 | Irinarassite | Ca3Sn2(SiO4)(AlO4)2 |
9.AD.25 | Menzerite-(Y) | (Y2Ca)Mg2(SiO4)3 |
9.AD.25 | Eltyubyuite | Ca12Fe3+10Si4O32Cl6 |
9.AD.25 | Blythite | Mn2+3Mn3+2[SiO4]3 |
9.AD.25 | Skiagite | Fe2+3Fe3+2[SiO4]3 |
9.AD.25 | Hutcheonite | Ca3Ti2(SiO4)(AlO4)2 |
9.AD.25 | UM1984-37-SiO:CrMn | Mn2+3Cr3+2(SiO4)3 |
9.AD.25 | Rubinite | Ca3Ti3+2Si3O12 |
9.AD.25 | Nikmelnikovite | Ca12(Fe2+Fe3+3Al3◻)[SiO4]6[◻(OH)4]5◻4 |
9.AD.30 va | Auerlite | near Th(Si,P)O4 |
9.AD.30 | Coffinite | U(SiO4) · nH2O |
9.AD.30 | Hafnon | HfSiO4 |
9.AD.30 | Thorite | Th(SiO4) |
9.AD.30 | Zircon | Zr(SiO4) |
9.AD.30 | Stetindite-(Ce) | Ce(SiO4) |
9.AD.35 | Huttonite | ThSiO4 |
9.AD.35 | Tombarthite-(Y) | Y4(Si,H4)4O12-x(OH)4+2x |
9.AD.40 | Eulytine | Bi4(SiO4)3 |
9.AD.45 | Reidite | ZrSiO4 |
Fluorescence of Jeffbenite
none
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.
Internet Links for Jeffbenite
mindat.org URL:
https://www.mindat.org/min-46574.html
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References for Jeffbenite
Localities for Jeffbenite
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).
Struck out - Mineral was erroneously reported from this locality.
Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.
All localities listed without proper references should be considered as questionable.
Brazil (TL) | |
| Hålenius et al. (2015) +2 other references |
Hayman et al. (2005) | |
Guinea | |
| Nestola et al. (2016) |
Romania | |
| Onac et al. (2003) |
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