Georgiadesite
A valid IMA mineral species - grandfathered
This page is currently not sponsored. Click here to sponsor this page.
About Georgiadesite
Formula:
Pb4(As3+O3)Cl4(OH)
The As was originally assumed to be pentavalent.
Colour:
White, brownish yellow; colourless in transmitted light.
Lustre:
Resinous
Hardness:
3½
Specific Gravity:
6.3
Crystal System:
Monoclinic
Name:
Named for George Georgiadès (1861-1918) graduated from the École Supérieure des Mines in Paris in 1888. He worked in Greece for various Greek and French companies and published scientific studies on mineralogy in French. George Géorgiadès was notably chief engineer of the "Société des Usines métallurgiques du Laurium" from 1888 to 1905, later directed the factory of the "Société (française) universelle des explosives et des produits chimiques" at Lavrion (1907-1908), created his own mining studies firm (located in Athens, 9, Rue Ophtalmiatrion) and was an advisor to several other mining companies.
This page provides mineralogical data about Georgiadesite.
Unique Identifiers
Mindat ID:
1677
Long-form identifier:
mindat:1:1:1677:9
IMA Classification of Georgiadesite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Pb2+4(As3+O3)Cl4(OH)
First published:
1907
Classification of Georgiadesite
4.JB.70
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
J : Arsenites, antimonites, bismuthites, sulfites, selenites, tellurites; iodates
B : Arsenites, antimonites, bismuthites; with additional anions, without H2O
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
J : Arsenites, antimonites, bismuthites, sulfites, selenites, tellurites; iodates
B : Arsenites, antimonites, bismuthites; with additional anions, without H2O
41.1.3.1
41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
1 : (AB)m(XO4)pZq, where m:p > 4:1
41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
1 : (AB)m(XO4)pZq, where m:p > 4:1
22.2.13
22 : Phosphates, Arsenates or Vanadates with other Anions
2 : Phosphates, arsenates or vanadates with chloride
22 : Phosphates, Arsenates or Vanadates with other Anions
2 : Phosphates, arsenates or vanadates with chloride
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 |
|---|---|---|
| Ggd | 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 Georgiadesite
Resinous
Transparency:
Translucent
Colour:
White, brownish yellow; colourless in transmitted light.
Hardness:
3½ on Mohs scale
Cleavage:
None Observed
Density:
6.3(3) g/cm3 (Measured) 6.39 g/cm3 (Calculated)
Optical Data of Georgiadesite
Type:
Biaxial (+)
RI values:
nα = 2.17 nβ = 2.17 nγ = 2.18
Max. Birefringence:
δ = 0.010
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.
No measured or calculated 2V is on file for this mineral, so the value used here (0°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
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.
No measured or calculated 2V is on file for this mineral, so the value used here (0°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Dispersion:
extreme
Optical Extinction:
Y = b; Z = c.
Comments:
2V very large.
Chemistry of Georgiadesite
Mindat Formula:
Pb4(As3+O3)Cl4(OH)
The As was originally assumed to be pentavalent.
The As was originally assumed to be pentavalent.
Element Weights:
Crystallography of Georgiadesite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/c
Cell Parameters:
a = 13.803(10) Å, b = 7.910(2) Å, c = 10.812(4) Å
β = 102.68(3)°
β = 102.68(3)°
Ratio:
a:b:c = 1.745 : 1 : 1.367
Unit Cell V:
1,151.68 ų (Calculated from Unit Cell)
Z:
1
Morphology:
Crystals stubby, pseudo-hexagonal tablets with a platy composite structure parallel to [100] (apparently due to lamellar twinning). {001} grooved and striated [010].
Twinning:
Apparent lamellar twinning on {100} and {104}
Crystallographic forms of Georgiadesite
Crystal Atlas:
Image Loading
Click on an icon to view
Georgiadesite no.1 - {110} - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by
www.smorf.nl.
Toggle
Edge Lines | Miller Indices | Axes
Transparency
Opaque | Translucent | Transparent
View
Along a-axis | Along b-axis | Along c-axis | Start rotation | Stop rotation
Edge Lines | Miller Indices | Axes
Transparency
Opaque | Translucent | Transparent
View
Along a-axis | Along b-axis | Along c-axis | Start rotation | Stop rotation
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.096 Å | (10) |
| 3.955 Å | (5) |
| 3.164 Å | (5) |
| 6.33 Å | (3) |
| 5.30 Å | (3) |
| 4.031 Å | (3) |
| 3.773 Å | (3) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47d : [Arsenates, antimonates, selenates, bismuthinates] | |
| 47g : [Halogen-bearing surface weathering minerals] | |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 56 : Slag and smelter minerals (see also #51 and #55) |
Type Occurrence of Georgiadesite
Place of Conservation of Type Material:
National School of Mines, Paris, France; American Museum of Natural History, New York City, New York, 28427; National Museum of Natural History, Washington, D.C., USA, 137839, 145938.
Geological Setting of Type Material:
N/A (occurred in altered lead slag)
Associated Minerals at Type Locality:
Synonyms of Georgiadesite
Other Language Names for Georgiadesite
Common Associates
Associations Based on Photo Data:
| 17 photos of Georgiadesite associated with Paralaurionite | PbCl(OH) |
| 7 photos of Georgiadesite associated with Nealite | Pb4Fe2+(As3+O3)2Cl4 · 2H2O |
| 2 photos of Georgiadesite associated with Phosgenite | Pb2CO3Cl2 |
| 2 photos of Georgiadesite associated with Aragonite | CaCO3 |
| 1 photo of Georgiadesite associated with Galena | PbS |
| 1 photo of Georgiadesite associated with Calcite | CaCO3 |
| 1 photo of Georgiadesite associated with Laurionite | PbCl(OH) |
| 1 photo of Georgiadesite associated with Diaboleite | Pb2CuCl2(OH)4 |
| 1 photo of Georgiadesite associated with Matlockite | PbFCl |
Related Minerals - Strunz-mindat Grouping
| 4.JB. | Cuyaite | Ca2Mn3+As3+14O24Cl |
| 4.JB. | Brattforsite | Mn19(AsO 3)12Cl2 |
| 4.JB.05 | Fetiasite | (Fe3+,Fe2+,Ti)3(As2O5)O2 |
| 4.JB.10 | Manganarsite | Mn3(As2O4)(OH)4 |
| 4.JB.15 | 'UM1984-09-AsO:ClHMn' | Mn10As6O18(OH)Cl |
| 4.JB.15 | Magnussonite | Mn2+10(As3+O3)6(OH,Cl)2 |
| 4.JB.20 | Armangite | Mn2+26(AsO3)14(HAsO3)4(CO3) |
| 4.JB.25 | Nanlingite | Na(Ca5Li)Mg12(AsO3)2[Fe(AsO3)6]F14 |
| 4.JB.30 | Asbecasite | Ca3(Ti,Sn4+)Be2(AsO3)6(SiO4)2 |
| 4.JB.35 | Stenhuggarite | CaFeSb(AsO3)2O |
| 4.JB.40 | Trigonite | Pb3Mn2+(AsO3)2(HAsO3) |
| 4.JB.45 | Finnemanite | Pb5(AsO3)3Cl |
| 4.JB.50 | Gebhardite | Pb8(As2O5)2OCl6 |
| 4.JB.55 | Graeserite | Fe3+4Ti3As3+O13(OH) |
| 4.JB.55 | Tomichite | (V,Fe)4Ti3AsO13(OH) |
| 4.JB.55 | Derbylite | Fe3+4Ti3Sb3+O13(OH) |
| 4.JB.60 | Hemloite | (Ti,V3+,Fe3+,Al)12(As3+,Sb3+)2O23(OH) |
| 4.JB.65 | Freedite | Cu+Pb8(AsO3)2O3Cl5 |
| 4.JB.75 | Szklaryite | ◻Al6BAs3+3O15 |
| 4.JB.75 | Ekatite | (Fe3+,Fe2+,Zn)12(AsO3)6(AsO3,HSiO4)2(OH)6 |
| 4.JB.85 | Lepageite | Mn2+3(Fe3+7Fe2+4)O3[Sb3+5As3+8O34] |
| 4.JB.90 | Bianchiniite | Ba2(TiV)(As2O5)2OF |
Other Information
Notes:
Soluble in HNO3.
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 Georgiadesite
mindat.org URL:
https://www.mindat.org/min-1677.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Georgiadesite
Reference List:
Lacroix, Alfred, De Schulten, August Benjamin (1908) Note sur les minéraux plombifères des scories athéniennes du Laurion. Bulletin de Minéralogie, 31 (2). 79-90 doi:10.3406/bulmi.1908.3288
Roland C. Rouse, , Pete J. Dunn, (1983) New data on georgiadesite. Mineralogical Magazine, 47 (343) 219-220 doi:10.1180/minmag.1983.047.343.12
Dunn, Pete J., Fleischer, Michael, Francis, Carl A., Langley, Richard H., Kissin, Stephen A., Shigley, Hames E., Vanko, David A., Zilczer, Janet A. (1984) New mineral names. American Mineralogist, 69 (7-8) 810-815 p.815
Localities for Georgiadesite
Showing 7 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.
Greece | |
| van Kalmthout (2012) |
| |
| Grolig et al. (1978) +3 other references | |
| Gelaude et al. (1996) |
| Lacroix et al. (1908) +2 other references | |
Italy | |
| Muenchener Micromounter-Lithothek |
Slovakia | |
| Ďuďa R. (1992) |
Quick NavTopAbout GeorgiadesiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystallographic forms X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Vrysaki Point slag locality, Velatouri, Lavreotiki, East Attica, Attica, Greece