Eriochalcite
A valid IMA mineral species - grandfathered
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About Eriochalcite
Formula:
CuCl2 · 2H2O
Colour:
Bluish green, greenish blue, yellowish tint at times.
Lustre:
Vitreous
Hardness:
2½
Specific Gravity:
2.47
Crystal System:
Orthorhombic
Name:
From the Greek έριου, wool, and χαλκός, copper, in allusion to the form of aggregation of the original Vesuvius material.
A secondary, water-soluble mineral.
Unique Identifiers
Mindat ID:
1398
Long-form identifier:
mindat:1:1:1398:3
IMA Classification of Eriochalcite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Cu2+Cl2·2H2O
First published:
1870
Classification of Eriochalcite
3.BB.05
3 : HALIDES
B : Simple halides, with H2O
B : M:X = 1:2
3 : HALIDES
B : Simple halides, with H2O
B : M:X = 1:2
9.2.8.1
9 : NORMAL HALIDES
2 : AX2
9 : NORMAL HALIDES
2 : AX2
8.2.3
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
2 : Halides of Cu
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
2 : Halides of Cu
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 |
|---|---|---|
| Ech | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Eriochalcite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Eriochalcite
Vitreous
Transparency:
Transparent
Colour:
Bluish green, greenish blue, yellowish tint at times.
Hardness:
2½ on Mohs scale
Cleavage:
Perfect
On {110} perfect; on {001} good.
On {110} perfect; on {001} good.
Fracture:
Conchoidal
Density:
2.47 g/cm3 (Measured) 2.55 g/cm3 (Calculated)
Optical Data of Eriochalcite
Type:
Biaxial (+)
RI values:
nα = 1.646 nβ = 1.685 nγ = 1.745
2V:
Measured: 75° , Calculated: 82°
Max. Birefringence:
δ = 0.099
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:
weak
Chemistry of Eriochalcite
Mindat Formula:
CuCl2 · 2H2O
Element Weights:
Elements listed:
Crystallography of Eriochalcite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pmna
Setting:
Pmna
Cell Parameters:
a = 8.047 Å, b = 3.725 Å, c = 7.376 Å
Ratio:
a:b:c = 2.16 : 1 : 1.98
Unit Cell V:
221.10 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Lichen-like aggregates of crystals elongated [01]. The center of these aggregates is occupied by small, deeply grooved spire-like cvrystals, often bent or entirely recurved as with gypsum "flowers"; wool-like aggregates.
Twinning:
On {021}, as nearly rectangular penetration twins.
Comment:
Also given as (Pbmn setting): a = 7.38, b = 8.04, c = 3.72 A.
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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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) |
|---|---|---|---|---|---|---|---|
| 0010986 | Eriochalcite | Brownstein S, Han N F, Gabe E, LePage Y (1989) A redetermination of the crystal structure of cupric chloride dihydrate Zeitschrift fur Kristallographie 189 13-15 |  | 1989 | synthetic | 0 | 293 |
| 0010555 | Eriochalcite | MacGillavry C H, Bijvoet J M (1936) Die kristallstruktur der cadmium-und quecksilber-diammin-dihalogenide Zeitschrift fur Kristallographie 94 231-245 | | 1936 | synthetic | 0 | 293 |
| 0016637 | Eriochalcite | Peterson S, Levy H (1957) Proton positions in Cu Cl2 (H2 O)2 by neutron diffraction _cod_database_code 1008760 Journal of Chemical Physics 26 220-221 | 1957 | 0 | 293 | ||
| 0017922 | Eriochalcite | Harker D (1936) The Crystal Structure of Cupric Chloride Dihydrate Cu Cl2 (H2 O)2 _cod_database_code 1011014 Zeitschrift fur Kristallographie 93 136-145 | 1936 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.476 Å | (100) |
| 4.050 Å | (56) |
| 3.093 Å | (40) |
| 2.638 Å | (82) |
| 2.2088 Å | (29) |
| 2.0240 Å | (22) |
| 1.6048 Å | (23) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 45b : [Other oxidized fumarolic minerals] | |
| 47a : [Near-surface hydration of prior minerals] | |
| 47g : [Halogen-bearing surface weathering minerals] | |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 55 : Anthropogenic mine minerals |
Type Occurrence of Eriochalcite
Place of Conservation of Type Material:
Harvard University, Cambridge, Massachusetts, USA, 97927.
Geological Setting of Type Material:
Active volcanic fumaroles.
Synonyms of Eriochalcite
Other Language Names for Eriochalcite
Common Associates
Associations Based on Photo Data:
| 4 photos of Eriochalcite associated with Amarantite | Fe3+2(SO4)2O · 7H2O |
| 4 photos of Eriochalcite associated with Chalcanthite | CuSO4 · 5H2O |
| 3 photos of Eriochalcite associated with Riotintoite | Al(SO4)(OH) · 3H2O |
| 3 photos of Eriochalcite associated with Bandylite | Cu[B(OH)4]Cl |
| 2 photos of Eriochalcite associated with Vendidaite | Al2(SO4)(OH)3Cl · 6H2O |
| 2 photos of Eriochalcite associated with Klyuchevskite | K3Cu3(Fe3+,Al)(SO4)4O2 |
| 2 photos of Eriochalcite associated with Chalcocyanite | CuSO4 |
| 1 photo of Eriochalcite associated with Belloite | Cu(OH)Cl |
Related Minerals - Strunz-mindat Grouping
| 3.BB. | Králíkite | BaCl2 · 2H2O |
| 3.BB.10 | Rokühnite | FeCl2 · 2H2O |
| 3.BB.15 | Bischofite | MgCl2 · 6H2O |
| 3.BB.20 | Nickelbischofite | NiCl2 · 6H2O |
| 3.BB.25 | Sinjarite | CaCl2 · 2H2O |
| 3.BB.30 | Antarcticite | CaCl2 · 6H2O |
| 3.BB.35 | Tachyhydrite | CaMg2Cl6 · 12H2O |
| 3.BB.35 | Aravaipaite | Pb3AlF9 · H2O |
| 3.BB.40 | Ghiaraite | CaCl2 · 4H2O |
Other Information
Notes:
Readily soluble in water to a pale blue solution and in NH4OH to an intense blue solution.
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 Eriochalcite
mindat.org URL:
https://www.mindat.org/min-1398.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Eriochalcite
Reference List:
Scacchi (1884) Reale accademia delle scienze fisische e matematiche, Naples: 23: 158. (as eriocalco)
Groth, F. (1898) Tabellarische Übersicht der Einfachen Mineralien (4th ed.). Friedrich Vieweg und Sohn.p.52 - as erythrochalcit
Palache, Charles, Foshag, W. F. (1938) Antofagastite and bandylite, two new copper minerals from Chile. American Mineralogist, 23 (2) 85-90 (as antofagastite)
Frondel, Clifford (1950) On paratacamite and some related copper chlorides. Mineralogical Magazine and Journal of the Mineralogical Society, 29 (208) 34-45 doi:10.1180/minmag.1950.029.208.06
Brownstein, Sydney; Han, Nam Fong; Gabe, Eric; LePage, Yvon (1989) A redetermination of the crystal structure of cupric chloride dihydrate. Zeitschrift für Kristallographie, 189 (1-2). 13-15 doi:10.1524/zkri.1989.189.1-2.13
Frost, Ray L., Williams, Peter A., Kloprogge, J. Theo, Martens, Wayde (2003) Raman spectroscopy of the copper chloride minerals nantokite, eriochalcite and claringbullite – implications for copper corrosion. Neues Jahrbuch für Mineralogie - Monatshefte, 2003 (10) 433-445 doi:10.1127/0028-3649/2003/2003-0433
Localities for Eriochalcite
Showing 23 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.
Atlantic Ocean | |
| Gablina et al. (2018) |
Australia | |
| |
| Noble et al. (1983) +1 other reference |
Austria | |
| Bojar (1993) |
Chile | |
| Clark (1993) | |
| Malcherek et al. (2010) |
| 45 +1 other reference |
Hungary | |
| Mecsek-Oko |
Iran | |
| Khorasanipour et al. (2011) +1 other reference |
Italy (TL) | |
| Palache et al. (1951) |
| Pelloux (1927) +2 other references | |
| Fernando Caboni et al. (2024) |
| Fernando Caboni et al. (2024) | |
Peru | |
| Diaby et al. (2006) |
Poland | |
| Łukasz Kruszewski PXRD & EPMA data (2019) |
| Ł. Kruszewski (PXRD data) |
Russia | |
| Diederik Visser List #39 |
| Pekov (1998) | |
| Pekov et al. (2015) |
| Sharygin et al. (2018) |
Spain | |
| Valente et al. (2013) |
USA | |
| Grant et al. (2005) |
| Castor et al. (2004) |
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La Vendida Mine, Sierra Gorda, Antofagasta Province, Antofagasta, Chile