Gajardoite-(NH4)
A valid IMA mineral species
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Formula:
(NH4)As3+4O6Cl2(Ca0.5◻0.5)(H2O)5
Colour:
colourless (crystals) to white (aggregates)
Lustre:
Vitreous
Hardness:
1½
Specific Gravity:
2.583 (Calculated)
Crystal System:
Hexagonal
Member of:
Unique Identifiers
Mindat ID:
470941
Long-form identifier:
mindat:1:1:470941:7
GUID
(UUID V4):
(UUID V4):
893aa35a-9bd6-41e2-9c0a-7b22dc719ff8
IMA Classification of Gajardoite-(NH4)
Classification of Gajardoite-(NH4)
3.D0.
3 : HALIDES
D : Oxyhalides, hydroxyhalides and related double halides
0 :
3 : HALIDES
D : Oxyhalides, hydroxyhalides and related double halides
0 :
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 |
---|---|---|
Gaj-NH4 | 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 Gajardoite-(NH4)
Vitreous
Transparency:
Transparent
Colour:
colourless (crystals) to white (aggregates)
Streak:
white
Hardness:
1½ on Mohs scale
Comment:
ca.
Tenacity:
Brittle
Cleavage:
Perfect
on {001}
on {001}
Density:
2.583 g/cm3 (Calculated)
Optical Data of Gajardoite-(NH4)
Type:
Uniaxial (-)
RI values:
nω = 1.745(10) nε = 1.558(5)
Max Birefringence:
δ = 0.187
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
Chemistry of Gajardoite-(NH4)
Mindat Formula:
(NH4)As3+4O6Cl2(Ca0.5◻0.5)(H2O)5
Chemical Analysis
Oxide wt%:
1 | |
---|---|
(NH4)2O | 3.17 % |
Na2O | 0.40 % |
K2O | 1.07 % |
CaO | 5.28 % |
As2O3 | 67.25 % |
Cl | 12.21 % |
H2O | 15.30 % |
O=Cl | -2.76 % |
Total: | 101.92 % |
Empirical formulas:
Sample ID | Empirical Formula |
---|---|
1 | [(NH4)0.72Kv0.13Na0.08]Σ0.93Ca0.55As3+4O6Cl2.03(H2O)5 |
Sample references:
ID | Locality | Reference | Notes |
---|---|---|---|
1 | Khovu-Aksy Ni-Co deposit, Chedi-Kholsky District, Tuva, Russia | by EPMA, water content by stoichiometry; empirical formula basis: 4 As and 11 O atoms per formula unit |
Crystallography of Gajardoite-(NH4)
Crystal System:
Hexagonal
Class (H-M):
6/mmm (6/m 2/m 2/m) - Dihexagonal Dipyramidal
Space Group:
P6/mmm
Cell Parameters:
a = 5.263(3) Å, c = 16.078(5) Å
Ratio:
a:c = 1 : 3.055
Unit Cell V:
385.68 ų (Calculated from Unit Cell)
X-Ray Powder Diffraction
Powder Diffraction Data:
d-spacing | Intensity |
---|---|
16.08 Å | (34) |
5.36 Å | (34) |
4.565 Å | (41) |
4.386 Å | (19) |
3.466 Å | (23) |
3.020 Å | (42) |
2.637 Å | (100) |
2.360 Å | (25) |
Type Occurrence of Gajardoite-(NH4)
General Appearance of Type Material:
tiny, lamellar, coarsely hexagonal or irregular, curved, and divergent crystals, up to 0.01 mm in size, in groups, rosette-like clusters or spherulitic aggregates, up to 0.2 mm; intimately intergrown with annabergite, arsenolite, and pharmacolite
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 6022/1
Associated Minerals at Type Locality:
Relationship of Gajardoite-(NH4) to other Species
Member of:
Other Members of this group:
Cuatrocapaite-(K) | K3(NaMg◻)(As2O3)6Cl6 · 16H2O | Trig. 3m (3 2/m) : R3m |
Cuatrocapaite-(NH₄) | (NH4)3(NaMg◻)(As2O3)6Cl6 · 16H2O | Trig. 3m (3 2/m) : R3m |
Ermakovite | (NH4)(As2O3)2Br | Hex. 6/mmm (6/m 2/m 2/m) : P6/mmm |
Gajardoite | KCa0.5As3+4O6Cl2 · 5H2O | Hex. 6/mmm (6/m 2/m 2/m) : P6/mmm |
Lucabindiite | (K,NH4)As4O6(Cl,Br) | Hex. 6/mmm (6/m 2/m 2/m) : P6/mmm |
Mauriziodiniite | (NH4)(As2O3)2I | Hex. 6/mmm (6/m 2/m 2/m) : P6/mmm |
Russoite | (NH4)ClAs2O3(H2O)0.5 | Hex. 6 2 2 : P6 2 2 |
Torrecillasite | Na(As,Sb)3+4O6Cl | Orth. |
Related Minerals - Strunz-mindat Grouping
3.D0. | Cabvinite | Th2F7(OH) · 3H2O |
3.D0. | Uranoclite | (UO2)2(OH)2Cl2(H2O)4 |
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 Gajardoite-(NH4)
mindat.org URL:
https://www.mindat.org/min-470941.html
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References for Gajardoite-(NH4)
Reference List:
Localities for Gajardoite-(NH4)
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.
Russia (TL) | |
| Bosi et al. (2023) |