Eckerite
A valid IMA mineral species
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About Eckerite
Markus Ecker
Formula:
Ag2CuAsS3
Colour:
Reddish-brown
Lustre:
Metallic
Hardness:
2½ - 3
Specific Gravity:
5.313 (Calculated)
Crystal System:
Monoclinic
Name:
Named for Markus Ecker (b. 1966), mining engineer and mineral collector from Schiffweiler, Germany. He is an expert on the minerals from Lengenbach, Tsumeb and the Kalahari manganese field. He has discovered four new minerals. He is a Member of the Technical Commission of the Forschungs gemeinschaft Lengenbach (FGL, Lengenbach Research Association) and has published many articles on the locality.
Type Locality:
Isostructural with:
The crystal structure is topologically identical to that of xanthoconite and pyrostilpnite, with one of the three independent Ag positions dominated by Cu.
Compare the chemically similar keutschite.
In thin plates, transparent; in thick sections, opaque.
Compare the chemically similar keutschite.
In thin plates, transparent; in thick sections, opaque.
Unique Identifiers
Mindat ID:
46496
Long-form identifier:
mindat:1:1:46496:7
GUID
(UUID V4):
(UUID V4):
2c406a61-77fa-4c12-930d-7b97b2019929
IMA Classification of Eckerite
Approved
Approval year:
2014
First published:
2015
Classification of Eckerite
2.GA.
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
G : Sulfarsenites, sulfantimonites, sulfbismuthites
A : Neso-sulfarsenites, etc. without additional S
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
G : Sulfarsenites, sulfantimonites, sulfbismuthites
A : Neso-sulfarsenites, etc. without additional S
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 |
|---|---|---|
| Ekr | 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 Eckerite
Metallic
Transparency:
Transparent, Opaque
Colour:
Reddish-brown
Streak:
Dark orange-red
Hardness:
2½ - 3 on Mohs scale
Hardness:
VHN100=64 - 78 - Vickers
Comment:
~2½–3
Tenacity:
Brittle
Cleavage:
None Observed
Fracture:
Irregular/Uneven
Density:
5.313 g/cm3 (Calculated)
Comment:
Could not be measured due to small grain size.
Optical Data of Eckerite
Anisotropism:
Under crossed nicols: weak with greyish to light blue rotation tints
Reflectivity:
| Wavelength | R1 | R2 |
|---|---|---|
| 471.1nm | 27.6% | 31.7% |
| 548.3nm | 22.8% | 26.1% |
| 586.6nm | 21.5% | 24.5% |
| 652.3nm | 19.4% | 22.3% |
Graph shows reflectance levels at different wavelengths (in nm). Top of box is 100%. Peak reflectance is 31.7%.
R1 shown in black, R2 shown in red
Pleochroism:
Weak
Comments:
From light grey to a slightly bluish grey.
Chemistry of Eckerite
Mindat Formula:
Ag2CuAsS3
Elements listed:
Crystallography of Eckerite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/b
Setting:
C2/c
Cell Parameters:
a = 11.8643(3) Å, b = 6.2338(1) Å, c = 16.6785(4) Å
β = 110.842(3)°
β = 110.842(3)°
Ratio:
a:b:c = 1.903 : 1 : 2.675
Unit Cell V:
1152.81 ų
Z:
8
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.446 Å | (70) |
| 3.246 Å | (50) |
| 2.941 Å | (100) |
| 2.776 Å | (40) |
| 2.134 Å | (50) |
| 2.084 Å | (18) |
| 2.076 Å | (40) |
| 1.738 Å | (40) |
Comments:
From Type Description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-𝑇 alteration and/or metamorphism | |
| 33 : Minerals deposited by hydrothermal metal-rich fluids (see also [#12]) |
Type Occurrence of Eckerite
General Appearance of Type Material:
Euhedral crystals up to 300 μm across.
Place of Conservation of Type Material:
Type material is deposited in the collections of the Museo di Storia Naturale, Universita` di Firenze, Via La Pira 4, I-50121 Firenze, Italy, catalogue number 3144/I.
Associated Minerals at Type Locality:
Reference:
Bindi, L., Nestola, F., Graeser, S., Tropper, P., Raber, T. (2015) Eckerite, Ag2CuAsS3, a new Cu-bearing sulfosalt from Lengenbach quarry, Binn valley, Switzerland: description and crystal structure. Mineralogical Magazine: 79: 687-694.
Synonyms of Eckerite
Related Minerals - Strunz-mindat Grouping
| 2.GA. | Arsiccioite | AgHg2Tl(As,Sb)2S6 |
| 2.GA. | Pyradoketosite | Ag3SbS3 |
| 2.GA.05 | Proustite | Ag3AsS3 |
| 2.GA.05 | Pyrargyrite | Ag3SbS3 |
| 2.GA.10 | Pyrostilpnite | Ag3SbS3 |
| 2.GA.10 | Xanthoconite | Ag3AsS3 |
| 2.GA.15 | Samsonite | Ag4MnSb2S6 |
| 2.GA.20 | Skinnerite | Cu3SbS3 |
| 2.GA.20 | Wittichenite | Cu3BiS3 |
| 2.GA.20 | Bytízite | Cu3SbSe3 |
| 2.GA.25 | Lapieite | NiCuSbS3 |
| 2.GA.25 | Mückeite | NiCu(Bi,Sb)S3 |
| 2.GA.25 | Malyshevite | PdCuBiS3 |
| 2.GA.25 | Lisiguangite | PtCuBiS3 |
| 2.GA.25 | Roterbärite | PdBiCuSe3 |
| 2.GA.30 | Aktashite | Cu6Hg3As4S12 |
| 2.GA.30 | Gruzdevite | Cu6Hg3Sb4S12 |
| 2.GA.30 | Nowackiite | Cu6Zn3As4S12 |
| 2.GA.30 | Zhengminghuaite | Cu6Fe3As4S12 |
| 2.GA.35 | Laffittite | AgHgAsS3 |
| 2.GA.40 | Routhierite | Tl(Cu,Ag)(Hg,Zn)2(As,Sb)2S6 |
| 2.GA.40 | Stalderite | Tl(Cu,Ag)(Zn,Fe,Hg)2(As,Sb)2S6 |
| 2.GA.40 | Ralphcannonite | AgZn2TlAs2S6 |
| 2.GA.40 | Ferrostalderite | CuFe2TlAs2S6 |
| 2.GA.40 | Unnamed (Ag-Fe endmember of Routhierite Group) | AgFe2TlAs2S6 |
| 2.GA.45 | Erniggliite | Tl2SnAs2S6 |
| 2.GA.50 | Bournonite | PbCuSbS3 |
| 2.GA.50 | Seligmannite | PbCuAsS3 |
| 2.GA.50 | Součekite | PbCuBi(S,Se)3 |
| 2.GA.50 | Unnamed (Pb-Cu-Bi Selenide) | PbCuBiSe3 |
| 2.GA.50 | Cerromojonite | CuPbBiSe3 |
| 2.GA.55 | Eldragónite | Cu6BiSe4(Se2) |
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 Eckerite
mindat.org URL:
https://www.mindat.org/min-46496.html
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References for Eckerite
Reference List:
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2015) New minerals and nomenclature modifications approved in 2014 and 2015. Newsletter No 23. Mineralogical Magazine, 79 (1) 51-58 doi:10.1180/minmag.2015.079.1.05
Localities for Eckerite
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.
Germany | |
| Belendorff (2021) |
Switzerland (TL) | |
| Williams et al. (2015) +2 other references |
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Lengenbach Quarry, Fäld, Binn, Goms, Valais, Switzerland