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Stergiouite
A valid IMA mineral species
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About Stergiouite
Formula:
CaZn2(AsO4)2 · 4H2O
Colour:
White to colourless
Lustre:
Pearly
Hardness:
3
Specific Gravity:
3.1
Crystal System:
Monoclinic
Name:
Named for Vasilis Stergiou (born 1958), in recognition of his contributions to the mineralogy of the Lavrion deposits.
Structurally related to phosphophyllite and hopeite group.
Chemically resembles prosperite, lotharmeyerite, gaitite, zincroselite and austinite.
Chemically resembles prosperite, lotharmeyerite, gaitite, zincroselite and austinite.
Unique Identifiers
Mindat ID:
53372
Long-form identifier:
mindat:1:1:53372:6
IMA Classification of Stergiouite
Approved
IMA Formula:
CaZn2+2(As5+O4)2·4H2O
Approval year:
2019
First published:
2020
Classification of Stergiouite
8.CA.75
8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H2O
A : With small and large/medium cations
8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H2O
A : With small and large/medium cations
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 |
|---|---|---|
| Sgo | 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 Stergiouite
Pearly
Colour:
White to colourless
Streak:
White
Hardness:
3 on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
{100}
{100}
Fracture:
Irregular/Uneven
Density:
3.1(2) g/cm3 (Measured) 3.183 g/cm3 (Calculated)
Optical Data of Stergiouite
Type:
Biaxial (-)
RI values:
nα = 1.561(3) nβ = 1.619(3) nγ = 1.621(5)
Max. Birefringence:
δ = 0.060
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:
Moderate (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 (20°) 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 (20°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Dispersion:
Very weak, with n(red) < n(violet).
Optical Extinction:
α is oriented approx. perpendicular to (100).
β is parallel to [010].
β is parallel to [010].
Pleochroism:
Not Visible
Chemistry of Stergiouite
Mindat Formula:
CaZn2(AsO4)2 · 4H2O
Element Weights:
Crystallography of Stergiouite
Crystal System:
Monoclinic
Class (H-M):
m - Domatic
Space Group:
Pb
Setting:
Pc
Cell Parameters:
a = 9.4160(3) Å, b = 5.3000(3) Å, c = 10.8931(4) Å
β = 91.767(1)°
β = 91.767(1)°
Ratio:
a:b:c = 1.777 : 1 : 2.055
Unit Cell V:
543.36 ų (Calculated from Unit Cell)
Z:
2
Morphology:
The forms {100}, {100} are dominant, {010}, {001}, {001}, {101}, {101}, {101} and {101} are subordinate.
Twinning:
Type material - no twinning was observed but inversion twinning is inferred from the X-ray structure refinement.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 9.406 Å | (100) |
| 4.619 Å | (80) |
| 3.612 Å | (35) |
| 3.494 Å | (35) |
| 2.984 Å | (60) |
| 2.922 Å | (50) |
| 2.720 Å | (20) |
| 2.647 Å | (25) |
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] |
Type Occurrence of Stergiouite
General Appearance of Type Material:
Clusters of stacked, platy crystals. Individual plates rarely exceed 200 × 100 × 5 μm in size.
Place of Conservation of Type Material:
mineralogical collections of the Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria, inventory number O34.
Geological Setting of Type Material:
Oxidation of sphalerite and native arsenic and dissolution of surrounding calcite.
Synonyms of Stergiouite
Other Language Names for Stergiouite
Dutch:Stergiouiet
German:Stergiouit
Common Associates
Associations Based on Photo Data:
| 1 photo of Stergiouite associated with Pharmacolite | Ca(HAsO4) · 2H2O |
| 1 photo of Stergiouite associated with Native Sulphur | S8 |
| 1 photo of Stergiouite associated with Native Arsenic | As |
| 1 photo of Stergiouite associated with Stibiconite | Sb3+Sb5+2O6(OH) |
| 1 photo of Stergiouite associated with Dolomite | CaMg(CO3)2 |
Related Minerals - Strunz-mindat Grouping
| 8.CA. | Apexite | NaMg(PO4) · 9H2O |
| 8.CA. | Brandãoite | BeAl2(PO4)2(OH)2(H2O)5 |
| 8.CA. | Davidlloydite | Zn3(AsO4)2 · 4H2O |
| 8.CA.05 | Parafransoletite | Ca3Be2(PO4)2(PO3OH)2 · 4H2O |
| 8.CA.05 | Fransoletite | Ca3Be2(PO4)2(PO3OH)2 · 4H2O |
| 8.CA.10 | Ehrleite | Ca4Be3Zn2(PO4)6 · 9H2O |
| 8.CA.15 | Faheyite | Be2Mn2+Fe3+2(PO4)4 · 6H2O |
| 8.CA.20 | Mccrillisite | NaCs(Be,Li)Zr2(PO4)4 · 1-2H2O |
| 8.CA.20 | Gainesite | Na(Na,K)(Be,Li)Zr2(PO4)4 · 1.5-2H2O |
| 8.CA.20 | Selwynite | NaK(Be,Al)Zr2(PO4)4 · 2H2O |
| 8.CA.25 | Pahasapaite | Li8(Ca,Li,K)10.5Be24(PO4)24 · 38H2O |
| 8.CA.30 | Nizamoffite | Mn2+Zn2(PO4)2(H2O)4 |
| 8.CA.30 | Arsenohopeite | Zn3(AsO4)2 · 4H2O |
| 8.CA.30 | Hopeite | ZnZn2(PO4)2 · 4H2O |
| 8.CA.35 | Warikahnite | Zn3(AsO4)2 · 2H2O |
| 8.CA.40 | Phosphophyllite | Zn2Fe 2+(PO4)2 · 4H2O |
| 8.CA.42 | Steinmetzite | Zn2Fe3+(PO4)2(OH) · 3H2O |
| 8.CA.45 | Parascholzite | CaZn2(PO4)2 · 2H2O |
| 8.CA.45 | Scholzite | CaZn2(PO4)2 · 2H2O |
| 8.CA.50 | Keyite | Cu2+3Zn4Cd2(AsO4)6 · 2H2O |
| 8.CA.55 | Pushcharovskite | K0.6Cu18[AsO2(OH)2]4[AsO3OH]10(AsO4)(OH)9.6 · 18.6H2O |
| 8.CA.60 | Prosperite | Ca2Zn4(AsO4)4 · H2O |
| 8.CA.65 | Gengenbachite | KFe3+3(PO3OH)4[PO2(OH)2]2 · 6H2O |
| 8.CA.70 | Parahopeite | Zn3(PO4)2 · 4H2O |
| 8.CA.70 | Reaphookhillite | MgZn2(PO4)2 · 4H2O |
| 8.CA.80 | Limousinite | BaCa[Be4P4O16] · 6H2O |
| 8.CA.85 | Minjiangite | BaBe2(PO4)2 |
| 8.CA.85 | Wilancookite | (Ba5Li2◻)Ba6Be24P24O96 · 26H2O |
Fluorescence of Stergiouite
Not fluorescent
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 Stergiouite
mindat.org URL:
https://www.mindat.org/min-53372.html
Please feel free to link to this page.
Please feel free to link to this page.
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Mineral Dealers:
References for Stergiouite
Reference List:
Miyawaki, Ritsuro, Hålenius, Ulf, Hatert, Frédéric, Pasero, Marco, Mills, Stuart J. (2019) IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) NEWSLETTER 47. European Journal of Mineralogy, 31 (1) 197-202 doi:10.1127/ejm/2019/0031-2839
Localities for Stergiouite
Showing 4 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.
Germany | |
| Stolze et al. (11/2020) |
Greece | |
| Rieck et al. (2020) |
| Rieck (n.d.) |
| European Journal of Mineralogy +2 other references |
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Plaka Mine No. 80, Plaka Mines, Plaka, Lavreotiki, East Attica, Attica, Greece