Gmalimite
A valid IMA mineral species
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About Gmalimite
Formula:
K6◻Fe2+24S27
Colour:
bronze
Lustre:
Metallic
Hardness:
3½
Specific Gravity:
3.79 (Calculated)
Crystal System:
Isometric
Member of:
Name:
Wadi Gmalim—a tributary of Wadi Hemar, also in the Hatrurim Basin
Type Locality:
Isostructural with:
K (or K◻) analogue of zoharite. Also K◻Cu-analogue of owensite.
Chemically related to bartonite and rasvumite.
The primary structural units of these minerals are M8S14 clusters, composed of MS4 tetrahedra surrounding a central MS6 octahedron. The M site is occupied by transition metals such as Fe, Cu, and Ni. These clusters are further connected via the edges of the MS4 tetrahedra, forming a close-packed cubic framework. The channels within this framework are filled by anion-centered polyhedra: SBa9 in zoharite and SK9 in gmalimite, respectively. In the M8S14 clusters, the M atoms are positioned so closely that their d orbitals can overlap, allowing the formation of metal–metal bonds. As a result, the transition metals in these clusters often adopt electron configurations that reflect additional electron density from their local bonding environment, similar to what is observed in pentlandite. Due to the presence of shared electrons in these metal–metal bonds, assigning fixed oxidation states—such as Fe2+/Fe3+ or Cu+/Cu2+—becomes challenging. Moreover, modeling the distribution of mixed-valence cations (Fe2+/3+, Cu+/2+, and Ni2+) across the two distinct M sites—one located in the MS6 octahedron and the other in the MS4 tetrahedra—often results in ambiguous outcomes. Consequently, it is difficult to define an idealized end-member formula for these minerals.
Chemically related to bartonite and rasvumite.
The primary structural units of these minerals are M8S14 clusters, composed of MS4 tetrahedra surrounding a central MS6 octahedron. The M site is occupied by transition metals such as Fe, Cu, and Ni. These clusters are further connected via the edges of the MS4 tetrahedra, forming a close-packed cubic framework. The channels within this framework are filled by anion-centered polyhedra: SBa9 in zoharite and SK9 in gmalimite, respectively. In the M8S14 clusters, the M atoms are positioned so closely that their d orbitals can overlap, allowing the formation of metal–metal bonds. As a result, the transition metals in these clusters often adopt electron configurations that reflect additional electron density from their local bonding environment, similar to what is observed in pentlandite. Due to the presence of shared electrons in these metal–metal bonds, assigning fixed oxidation states—such as Fe2+/Fe3+ or Cu+/Cu2+—becomes challenging. Moreover, modeling the distribution of mixed-valence cations (Fe2+/3+, Cu+/2+, and Ni2+) across the two distinct M sites—one located in the MS6 octahedron and the other in the MS4 tetrahedra—often results in ambiguous outcomes. Consequently, it is difficult to define an idealized end-member formula for these minerals.
Unique Identifiers
Mindat ID:
53672
Long-form identifier:
mindat:1:1:53672:3
IMA Classification of Gmalimite
Approved
IMA Formula:
K6◻Fe2+24S2-27
Approval year:
2019
Type description reference:
[1]Galuskina, Irina O.; Krüger, Biljana; Galuskin, Evgeny V.; Krüger, Hannes; Vapnik, Yevgeny; Murashko, Mikhail; Banasik, Kamila; Agakhanov, Atali A. (2025) Zoharite, (Ba,K)6(Fe,Cu,Ni)25S27, and Gmalimite, K6□Fe2+24S27—New Djerfisherite Group Minerals from Gehlenite-Wollastonite Paralava, Hatrurim Complex, Israel. Minerals, 15 (6). 564 doi:10.3390/min15060564
Classification of Gmalimite
2.FC.05
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
F : Sulfides of arsenic, alkalies; sulfides with halide, oxide, hydroxide, H2O
C : With Cl, Br, I (halide-sulfides)
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
F : Sulfides of arsenic, alkalies; sulfides with halide, oxide, hydroxide, H2O
C : With Cl, Br, I (halide-sulfides)
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 |
|---|---|---|
| Gma | 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 Gmalimite
Metallic
Transparency:
Opaque
Colour:
Bronze
Streak:
Dark-gray
Hardness:
3½ on Mohs scale
Hardness:
VHN25=190(6) kg/mm2 - Vickers
Tenacity:
Brittle
Cleavage:
None Observed
Parting:
none
Fracture:
Irregular/Uneven, Conchoidal
Comment:
Tenacity is brittle and sectile
Density:
3.79 g/cm3 (Calculated)
Optical Data of Gmalimite
Reflectivity:
| Wavelength | R1 (%) | R2 (%) |
|---|---|---|
| 470nm | 22.2% | 21.5% |
| 546nm | 25.1% | 24.6% |
| 589nm | 26.3% | 25.9% |
| 650nm | 27.7% | 26.3% |
Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 27.7%.
R1 shown in black, R2 shown in red
Colour in reflected light:
gray color with an olive tinge
Chemistry of Gmalimite
Mindat Formula:
K6◻Fe2+24S27
Elements listed:
Crystallography of Gmalimite
Crystal System:
Isometric
Class (H-M):
m3m(4/m32/m) - Hexoctahedral
Space Group:
Pm3m
Setting:
Pm3m
Cell Parameters:
a = 10.3486(1) Å
Unit Cell V:
1,108.27 ų (Calculated from Unit Cell)
Z:
1
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 10.357 Å | (91) |
| 7.323 Å | (33) |
| 5.979 Å | (59) |
| 3.123 Å | (56) |
| 2.990 Å | (58) |
| 2.376 Å | (50) |
| 1.831 Å | (100) |
| 1.057 Å | (14) |
Reference:
[1]Galuskina, Irina O.; Krüger, Biljana; Galuskin, Evgeny V.; Krüger, Hannes; Vapnik, Yevgeny; Murashko, Mikhail; Banasik, Kamila; Agakhanov, Atali A. (2025) Zoharite, (Ba,K)6(Fe,Cu,Ni)25S27, and Gmalimite, K6□Fe2+24S27—New Djerfisherite Group Minerals from Gehlenite-Wollastonite Paralava, Hatrurim Complex, Israel. Minerals, 15 (6). 564 doi:10.3390/min15060564
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 35 : Ultra-alkali and agpaitic igneous rocks |
Type Occurrence of Gmalimite
General Appearance of Type Material:
grained aggregates confined to the peripheric parts of pyrrhotite nodules up to 100 μm in size
Place of Conservation of Type Material:
Collections of the Fersman Mineralogical Museum, Russian Academy of Sciences, Leninskiy Prospekt 18-2, Moscow 119071, Russia, registration number 5297/1
Geological Setting of Type Material:
gehlenite–wollastonite paralava with pyrrhotite nodules located in the Hatrurim pyrometamorphic complex, Negev Desert, Israel
Associated Minerals at Type Locality:
Reference:
[1]Galuskina, Irina O.; Krüger, Biljana; Galuskin, Evgeny V.; Krüger, Hannes; Vapnik, Yevgeny; Murashko, Mikhail; Banasik, Kamila; Agakhanov, Atali A. (2025) Zoharite, (Ba,K)6(Fe,Cu,Ni)25S27, and Gmalimite, K6□Fe2+24S27—New Djerfisherite Group Minerals from Gehlenite-Wollastonite Paralava, Hatrurim Complex, Israel. Minerals, 15 (6). 564 doi:10.3390/min15060564
Synonyms of Gmalimite
Other Language Names for Gmalimite
Relationship of Gmalimite to other Species
Member of:
Other Members of Djerfisherite Group:
| 'Cu-djerfisherite' | K6(Cu,Fe)25S26Cl | |
| Djerfisherite | K6(Fe,Cu,Ni)25S26Cl | Iso. m3m(4/m32/m) : Pm3m |
| Owensite | (Ba,Pb)6(Cu,Fe,Ni)25S27 | Iso. m3m(4/m32/m) : Pm3m |
| Thalfenisite | Tl6(Fe,Ni,Cu)25S26Cl | Iso. |
| Zoharite | (Ba,K)6(Fe,Cu,Ni)25S27 | Iso. m3m(4/m32/m) : Pm3m |
Common Associates
Associations Based on Photo Data:
| 1 photo of Gmalimite associated with Zoharite | (Ba,K)6(Fe,Cu,Ni)25S27 |
| 1 photo of Gmalimite associated with Pyrrhotite | Fe1-xS |
Related Minerals - Strunz-mindat Grouping
| 2.FC. | Demicheleite-(I) | BiSI |
| 2.FC.05 | Djerfisherite | K6(Fe,Cu,Ni)25S26Cl |
| 2.FC.05 | Owensite | (Ba,Pb)6(Cu,Fe,Ni)25S27 |
| 2.FC.05 | Thalfenisite | Tl6(Fe,Ni,Cu)25S26Cl |
| 2.FC.05 | 'Cu-djerfisherite' | K6(Cu,Fe)25S26Cl |
| 2.FC.05 | Zoharite | (Ba,K)6(Fe,Cu,Ni)25S27 |
| 2.FC.10 | Bartonite | K6Fe20S26S |
| 2.FC.10 | Chlorbartonite | K6Fe24S26(Cl,S) |
| 2.FC.15d | Radtkeite | Hg2+3S2ICl |
| 2.FC.15a | Lavrentievite | Hg3S2Cl2 |
| 2.FC.15a | Corderoite | Hg2+3S2Cl2 |
| 2.FC.15a | 'Arzakite' | Hg2+3S2(Br,Cl)2 |
| 2.FC.15c | Grechishchevite | Hg2+3S2(Br,Cl,I)2 |
| 2.FC.15b | Kenhsuite | Hg2+3S2Cl2 |
| 2.FC.20b | Iltisite | HgAgSCl |
| 2.FC.20c | Perroudite | Hg5Ag4S5(I,Br)2Cl2 |
| 2.FC.20a | Capgaronnite | AgHgClS |
| 2.FC.20d | Hanauerite | AgHgSI |
| 2.FC.25 | Demicheleite-(Cl) | BiSCl |
| 2.FC.25 | Demicheleite-(Br) | BiSBr |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 0.0000% | 0 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 9.6119% | 2,980 | β, γ |
For comparison:
- Banana: ~15 Bq per fruit
- Granite: 1,000–3,000 Bq/kg
- EU exemption limit: 10,000 Bq/kg
Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.
Interactive Simulator:
Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!
Activity: –
| Distance | Dose rate | Risk |
|---|---|---|
| 1 cm | ||
| 10 cm | ||
| 1 m |
The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μshield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).
D = ((AU × ΓU) + (ATh × ΓTh) + (AK × ΓK)) / r2 × μshield
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 Gmalimite
mindat.org URL:
https://www.mindat.org/min-53672.html
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References for Gmalimite
Reference List:
Miyawaki, Ritsuro, Hatert, Frédéric, Pasero, Marco, Mills, Stuart J. (2019) CNMNC Newsletter No 50, New minerals and nomenclature modifications approved in 2019. Mineralogical Magazine, 83 (4) 615-620 doi:10.1180/mgm.2019.46
[1]Galuskina, Irina O.; Krüger, Biljana; Galuskin, Evgeny V.; Krüger, Hannes; Vapnik, Yevgeny; Murashko, Mikhail; Banasik, Kamila; Agakhanov, Atali A. (2025) Zoharite, (Ba,K)6(Fe,Cu,Ni)25S27, and Gmalimite, K6□Fe2+24S27—New Djerfisherite Group Minerals from Gehlenite-Wollastonite Paralava, Hatrurim Complex, Israel. Minerals, 15 (6). 564 doi:10.3390/min15060564
Localities for Gmalimite
Showing 2 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.
Israel (TL) | |
| Miyawaki et al. (2019) +1 other reference |
| Galuskina et al. (2025) |
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Wadi Halamish, Hatrurim Basin, Tamar Regional Council, Beersheba Subdistrict, Southern District, Israel