Esperite
A valid IMA mineral species
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About Esperite
Esper Signius Larsen, Jr
Formula:
PbCa2Zn3(SiO4)3
Colour:
White, off-white, pale tan
Lustre:
Sub-Vitreous, Greasy
Hardness:
5
Specific Gravity:
4.28 - 4.42
Crystal System:
Monoclinic
Name:
Originally named calcium-larsenite named by Charles Palache, Lawson Bauer, and Harry Berman in 1928 in honor of Esper S. Larsen, Sr in allusion to its supposed relationship to larsenite. Re-named in 1965 by Paul Brian Moore and Paul H. Ribbe for Esper Signius Larsen, Jr. [March 14, 1879 Astoria, Oregon, USA - March 8, 1961 Washington, DC, USA], petrologist and Professor of Geology at Harvard University, Cambridge, Massachusetts, USA. (see also larsenite).
Isostructural with:
Massive off-white material in typical Franklin ore (willemite, zincite, franklinite, calcite) with hardystonite and clinohedrite.
Often found pseudomorphically replacing hardystonite, in part as feathery incursions into massive hardystonite, and as complete replacements, including of embedded hardystonite crystals. These features are readily evident under UV light.
Visit gemdat.org for gemological information about Esperite.
Often found pseudomorphically replacing hardystonite, in part as feathery incursions into massive hardystonite, and as complete replacements, including of embedded hardystonite crystals. These features are readily evident under UV light.
Visit gemdat.org for gemological information about Esperite.Unique Identifiers
Mindat ID:
1412
Long-form identifier:
mindat:1:1:1412:6
Similar Names
| Asperite | A rock subtype |
IMA Classification of Esperite
Approved
IMA Formula:
Pb2+Ca2(Zn2+SiO4)3
Approval year:
1964
First published:
1928
Classification of Esperite
9.AB.15
9 : SILICATES (Germanates)
A : Nesosilicates
B : Nesosilicates without additional anions; cations in [4] and greater coordination
9 : SILICATES (Germanates)
A : Nesosilicates
B : Nesosilicates without additional anions; cations in [4] and greater coordination
Dana 7th ed.:
51.2.1.3
51.2.1.3
51 : NESOSILICATES Insular SiO4 Groups Only
2 : Insular SiO4 Groups Only with cations in [4] as well as >[4]
51 : NESOSILICATES Insular SiO4 Groups Only
2 : Insular SiO4 Groups Only with cations in [4] as well as >[4]
14.7.19
14 : Silicates not Containing Aluminum
7 : Silicates of Ba, Sr and Zn
14 : Silicates not Containing Aluminum
7 : Silicates of Ba, Sr and Zn
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 |
|---|---|---|
| Epr | 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 Esperite
Sub-Vitreous, Greasy
Transparency:
Transparent, Translucent
Colour:
White, off-white, pale tan
Comment:
My be orange or light brown due to finr-grained inclusions of andradite or zincite
Streak:
White
Hardness:
5 on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
Distinct on {010} and {100}, poor on {101}
Distinct on {010} and {100}, poor on {101}
Fracture:
Irregular/Uneven
Density:
4.28 - 4.42 g/cm3 (Measured) 4.25 g/cm3 (Calculated)
Optical Data of Esperite
Type:
Biaxial (-)
RI values:
nα = 1.762 nβ = 1.770 nγ = 1.774
2V:
Measured: 5° to 40°
Birefringence:
0.012
Max. Birefringence:
δ = 0.012
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:
very strong
Pleochroism:
Non-pleochroic
Chemistry of Esperite
Mindat Formula:
PbCa2Zn3(SiO4)3
Element Weights:
Common Impurities:
Fe,Mn,Mg
Crystallography of Esperite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Cell Parameters:
a = 17.628 Å, b = 8.27 Å, c = 30.52 Å
β = 90°
β = 90°
Ratio:
a:b:c = 2.132 : 1 : 3.69
Unit Cell V:
4449.31 ų
Z:
12
Morphology:
Coarse granular aggregates, massive, to 9 cm
Twinning:
Commonly triply twinned (~60° rotational twinning around the b axis).
Comment:
P21/n
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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CIF File Best | x | y | z | a | b | c
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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) |
|---|---|---|---|---|---|---|---|
| 0005046 | Esperite | Tait K T, Yang H, Downs R T, Li C, Pinch W W (2010) The crystal structure of esperite, with a revised chemical formula, PbCa2(ZnSiO4)3, isostructural with beryllonite American Mineralogist 95 699-705 | 2010 | Franklin, New Jersey, USA | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.62 Å | (45) |
| 4.73 Å | (10) |
| 4.41 Å | (16) |
| 3.82 Å | (16) |
| 3.76 Å | (8) |
| 3.64 Å | (16) |
| 3.363 Å | (25) |
| 3.22 Å | (18) |
| 3.017 Å | (100) |
| 2.958 Å | (20) |
| 2.884 Å | (35) |
| 2.805 Å | (4) |
| 2.675 Å | (8) |
| 2.597 Å | (4) |
| 2.543 Å | (75) |
| 2.490 Å | (4) |
| 2.434 Å | (8) |
| 2.367 Å | (40) |
| 2.314 Å | (4) |
| 2.237 Å | (4) |
| 2.205 Å | (4) |
| 2.169 Å | (8) |
| 2.145 Å | (4) |
| 2.118 Å | (8) |
| 2.051 Å | (14) |
| 2.015 Å | (10) |
| 1.994 Å | (4) |
| 1.944 Å | (45) |
Reference:
Comments:
ICDD 16-373 From Franklin, New Jersey material
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits |
Type Occurrence of Esperite
General Appearance of Type Material:
Massive off-white material in massive ore.
Place of Conservation of Type Material:
n.d.
Geological Setting of Type Material:
Metamorphosed stratiform zinc-iron-manganese orebody.
Associated Minerals at Type Locality:
Synonyms of Esperite
Other Language Names for Esperite
Common Associates
Associations Based on Photo Data:
| 151 photos of Esperite associated with Willemite | Zn2SiO4 |
| 132 photos of Esperite associated with Franklinite | Zn2+Fe3+2O4 |
| 98 photos of Esperite associated with Calcite | CaCO3 |
| 96 photos of Esperite associated with Hardystonite | Ca2Zn[Si2O7] |
| 44 photos of Esperite associated with Zincite | ZnO |
| 23 photos of Esperite associated with Clinohedrite | CaZn(SiO4) · H2O |
| 6 photos of Esperite associated with Glaucochroite | CaMn2+(SiO4) |
| 2 photos of Esperite associated with Hodgkinsonite | Mn2+Zn2(SiO4)(OH)2 |
| 1 photo of Esperite associated with Tephroite | Mn2+2(SiO4) |
| 1 photo of Esperite associated with Hancockite | (CaPb)(AlAlFe3+)O[Si2O7][SiO4](OH) |
Related Minerals - Strunz-mindat Grouping
| 9.AB.05 | Trimerite | CaMn2+2Be3(SiO4)3 |
| 9.AB.10 | Larsenite | PbZnSiO4 |
| 9.AB.20 | Rondorfite | Ca8Mg(SiO4)4Cl2 |
Fluorescence of Esperite
Bright yellow (SW UV)(Franklin); dull yellow (LW UV)
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.
Industrial Uses:
None
Internet Links for Esperite
mindat.org URL:
https://www.mindat.org/min-1412.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Esperite
Reference List:
Palache, C., Bauer, L. H., Berman, H. (1928) Larsenite and calcium-larsenite, new members of the chrysolite group, from Franklin, New Jersey. (Preliminary Notice) American Mineralogist, 13 (4) 142-144 (as calcium-larsenite)
Palache, C., Bauer, L. H., Berman, H. (1928) Larsenite, calcium-larsenite and associated minerals at Franklin, New Jersey. American Mineralogist, 13 (7) 334-340 (as calcium-larsenite)
Palache, C., Bauer, L. H., Berman, H. (1928) Larsenite and calcium-larsenite, new members of the chrysolite group, from Franklin, New Jersey. (Preliminary Notice) American Mineralogist, 13 (4) 142-144
Palache, Charles (1935) The minerals of Franklin and Sterling Hill, Sussex County, New Jersey. Professional Paper 180. US Geological Survey 135 pp. doi:10.3133/pp180 pp.81-82
Moore, Paul B., Ribbe, Paul H. (1965) A study of "calcium-larsenite" renamed esperite. American Mineralogist, 50 (9) 1170-1178
Localities for Esperite
Showing 5 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.
Bolivia | |
| Schnorrer-Köhler et al. (1990) |
USA | |
| Palache (1935) +1 other reference |
| Steven Phillips | |
| King (n.d.) +2 other references | |
| Palache (1935) +1 other reference |
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Franklin Mine, Franklin, Sussex County, New Jersey, USA