Esperanzaite
A valid IMA mineral species
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About Esperanzaite
Formula:
NaCa2Al2(AsO4)2(OH)F4 · 2H2O
Colour:
Pale blue-green
Lustre:
Vitreous
Hardness:
4½
Specific Gravity:
3.24
Crystal System:
Monoclinic
Name:
Named after the discovery locality, the La Esperanza Mine, Durango, Mexico.
This page provides mineralogical data about Esperanzaite.
Unique Identifiers
Mindat ID:
6919
Long-form identifier:
mindat:1:1:6919:5
IMA Classification of Esperanzaite
Approved
IMA Formula:
NaCa2Al2(As5+O4)2F4(OH)·2H2O
Approval year:
1998
First published:
1999
Classification of Esperanzaite
8.DM.05
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
M : With large and medium-sized cations, (OH, etc.):RO4 > 2:1
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
M : With large and medium-sized cations, (OH, etc.):RO4 > 2:1
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 |
|---|---|---|
| Epz | 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 Esperanzaite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Esperanzaite
Vitreous
Transparency:
Transparent, Translucent
Colour:
Pale blue-green
Streak:
White
Hardness:
4½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
Parallel to c.
Parallel to c.
Fracture:
None observed
Density:
3.24 g/cm3 (Measured) 3.36 g/cm3 (Calculated)
Optical Data of Esperanzaite
Type:
Biaxial (-)
RI values:
nα = 1.580(1) nβ = 1.588(1) nγ = 1.593(1)
2V:
Measured: 74° , Calculated: 76°
Max. Birefringence:
δ = 0.013
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.
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:
r < v moderate
Optical Extinction:
Y = b; X ∧ c = 35°; Z ∧ a = 50.5°.
Pleochroism:
Non-pleochroic
Chemistry of Esperanzaite
Mindat Formula:
NaCa2Al2(AsO4)2(OH)F4 · 2H2O
Element Weights:
Crystallography of Esperanzaite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/m
Setting:
P21/m
Cell Parameters:
a = 9.687(5) Å, b = 10.7379(6) Å, c = 5.5523(7) Å
β = 105.32°
β = 105.32°
Ratio:
a:b:c = 0.902 : 1 : 0.517
Unit Cell V:
557.02 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Botryoidal patches and radiating crystals in spheres.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
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) |
|---|---|---|---|---|---|---|---|
| 0005592 | Esperanzaite | Foord E E, Hughes J M, Cureton F E, Maxwell C H, Falster A U, Sommer A J, Hlava P F (1999) Esperanzaite, NaCa2Al2(AsO4)2F4(OH).2H2O, a new mineral species from the La Esperanza mine, Mexico: Descriptive mineralogy and atomic arrangement The Canadian Mineralogist 37 67-72 |  | 1999 | La Esperanza mine, Mexico | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.364 Å | (80) |
| 4.796 Å | (80) |
| 3.801 Å | (80) |
| 3.527 Å | (90) |
| 2.966 Å | (100) |
| 2.700 Å | (90) |
Comments:
La Esperanza mine, Durango, Mexico. The data are from the type description.
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] |
Type Occurrence of Esperanzaite
General Appearance of Type Material:
Botryoidal pale blue-green (seafoam green) patches up to 8 mm across and separated spheres up to 1.5 mm in diameter of radiating crystals.
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 171530.
Geological Setting of Type Material:
Found on an altered rhyolite.
Associated Minerals at Type Locality:
Synonyms of Esperanzaite
Other Language Names for Esperanzaite
Related Minerals - Strunz-mindat Grouping
| 8.DM. | Tomsquarryite | NaMgAl3(PO4)2(OH)6 · 8H2O |
| 8.DM. | Elliottite | NaMgAl3(PO4)2F6 · 9H2O |
| 8.DM. | Betpakdalite-FeFe | [Fe3+2 (H2O)15(OH)2Fe3+(H2O)6][Mo8As2Fe3+3O37] |
| 8.DM. | Penriceite | [Mg(H2O)6][Na(H2O)2Al3(PO4)2F6] · H2O |
| 8.DM. | Betpakdalite-CaMg | [Ca2(H2O)17Mg(H2O)6][Mo8As2Fe3+3O36(OH)] |
| 8.DM. | Chinnerite | [Mg(H2O)6]Na(H2O)2Al3(PO4)2F6 |
| 8.DM. | Sarrochite | [Ca4(H2O)38][Mo8P2Fe3+3O37(OH)] |
| 8.DM.05 | Morinite | NaCa2Al2(PO4)2(OH)F4 · 2H2O |
| 8.DM.10 | Alexshubnikovite | Ca2Cu9(AsO4)4(OH)9Cl(H2O)8 · 2H2O |
| 8.DM.10 | Tangdanite | Ca2Cu9(AsO4)4(SO4)0.5(OH)9 · 9H2O |
| 8.DM.10 | Tyrolite | Ca2Cu9(AsO4)4(CO3)(OH)8 · 11H2O |
| 8.DM.15 | Melkovite | [Ca2(H2O)15Ca(H2O)6][Mo8P2Fe3+3O36(OH)] |
| 8.DM.15 | Betpakdalite-NaCa | [Na2(H2O)17Ca(H2O)6][Mo6+8As5+2Fe3+3O34(OH)3] |
| 8.DM.15 | Betpakdalite-CaCa | [Ca2(H2O)17Ca(H2O)6][Mo6+8As5+2Fe3+3O36(OH)] |
| 8.DM.20 | Phosphovanadylite-Ba | Ba[V4+4P2O8(OH)8] · 12H2O |
| 8.DM.20 | Phosphovanadylite-Ca | Ca[V4+4P2O12(OH)4] · 12H2O |
| 8.DM.25 | Yukonite | Ca3Fe3+(AsO4)2(OH)3 · 5H2O |
| 8.DM.30 | Uduminelite | Ca3Al8(PO4)2O12 · 2H2O |
| 8.DM.35 | Aldermanite | [Mg(H2O)6][Na(H2O)2Al3(PO4)2(OH,F)6] · H2O |
| 8.DM.35 | 'Azovskite' | Fe3+3(PO4)(OH)6 or near |
| 8.DM.35 | Delvauxite | CaFe4(PO4,SO4)2(OH)8 · 4-6H2O not confirmed |
| 8.DM.40 | Santafeite | (Na,Ca,Sr)12(Mn2+,Fe3+,Al,Mg)8Mn4+8(VO4)16(OH,O)20 · 8H2O |
| 8.DM.55 | Tapiaite | Ca5Al2(AsO4)4(OH)4 · 12H2O |
| 8.DM.60 | Alcantarillaite | [Fe3+0.5(H2O)4][CaAs3+2(Fe3+2.5W6+0.5)(AsO4)2O7] |
Fluorescence of Esperanzaite
Not fluorescent.
Other Information
IR Spectrum:
Prominent absorptions at 3435, 1615, 1175, 844 and 832 cm-1, indicating OH, H2O, and AlOH. Also bands at 844 and 832 cm-1 due to AsO43-.
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 Esperanzaite
mindat.org URL:
https://www.mindat.org/min-6919.html
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References for Esperanzaite
Reference List:
Localities for Esperanzaite
Showing 1 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.
Mexico (TL) | |
| AmMin 85:263] +1 other reference |
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La Esperanza Mine, Francisco I. Madero, Pánuco de Coronado Municipality, Durango, Mexico