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Esperite

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Esper Signius Larsen, Jr
Formula:
PbCa2Zn3(SiO4)3
System:
Monoclinic
Colour:
White, off-white, pale ...
Hardness:
5
Name:
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.

Classification of Esperite

Approved 1964
9.AB.15

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]
14.7.19

14 : Silicates not Containing Aluminum
7 : Silicates of Ba, Sr and Zn
mindat.org URL:
http://www.mindat.org/min-1412.html
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First Recorded Occurrence of Esperite

General Appearance of First Recorded Material:
Massive off-white material in massive ore.
Year of Discovery:
1928
Geological Setting of First Recorded Material:
Metamorphosed stratiform zinc-iron-manganese orebody.
Associated Minerals at First Recorded Locality:

Physical Properties of Esperite

Sub-Vitreous, Greasy
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
White, off-white, pale tan
Streak:
White.
Hardness (Mohs):
5
Tenacity:
Brittle
Cleavage:
Distinct/Good
Distinct on {010} and {100}, poor on {101}
Fracture:
Irregular/Uneven
Density:
4.28 - 4.42 g/cm3 (Measured)    4.25 g/cm3 (Calculated)

Crystallography of Esperite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/m
Cell Parameters:
a = 17.628Å, b = 8.27Å, c = 30.52Å
β = 90°
Ratio:
a:b:c = 2.132 : 1 : 3.69
Unit Cell Volume:
V 4449.31 ų
Z:
12
Morphology:
Coarse granular aggregates, massive, to 9 cm
X-Ray Powder Diffraction Data:
d-spacingIntensity
7.62 (45)
3.363 (23)
3.017 (100)
2.884 (33)
2.534 (75)
2.367 (40)
1.944 (45)
Comments:
From Franklin, New Jersey material

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
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Very High
Dispersion:
very strong

Chemical Properties of Esperite

Formula:
PbCa2Zn3(SiO4)3
Essential elements:
All elements listed in formula:
Analytical Data:
First set based on Pb1.23(Ca2.89Mn0.08Mg0.06)Zn3.73Si3.98O16 and second set based on electron microprobe average of 10 analyses to Pb1.15(Ca2.80Mg0.09Mn0.08)2.97Zn3.80Si4.04O16
SiO2 (24.10),(25.3)
FeO (0.48), 0
MnO (0.57),(0.6)
ZnO (30.61),(32.3)
PbO (27.63),(26.8)
MgO (0.23),(0.4)
CaO (16.36),(16.4)
H2O (0.12)
Common Impurities:
Fe,Mn,Mg

Relationship of Esperite to other Species

9.AB.05TrimeriteCaMn22+Be3(SiO4)3
9.AB.10LarsenitePbZnSiO4
9.AB.20RondorfiteCa8Mg(SiO4)4Cl2
14.7.1SanborniteBa2(Si4O10)
14.7.2KrauskopfiteBaSi2O5 · 3H2O
14.7.3WalstromiteBaCa2(Si3O9)
14.7.4MacdonalditeBaCa4Si16O36(OH)2 · 10H2O
14.7.5EricssoniteBaMn22+Fe3+(Si2O7)O(OH)
14.7.6Ericssonite-2OBaMn22+Fe3+(Si2O7)O(OH)
14.7.7GillespiteBaFe2+[Si4O10]
14.7.8AndrémeyeriteBaFe22+(Si2O7)
14.7.9PellyiteBa2Ca(Fe,Mg)2Si6O17
14.7.10TaikaniteSr3BaMn22+(Si4O12)O2
14.7.11WillemiteZn2SiO4
14.7.12HemimorphiteZn4Si2O7(OH)2 · H2O
14.7.13ZincsiliteZn3(Si4O10)(OH)2 · 4H2O
14.7.14HardystoniteCa2Zn(Si2O7)
14.7.15PetedunniteCa(Zn,Mn2+,Mg,Fe2+)Si2O6
14.7.16ClinohedriteCaZn(SiO4) · H2O
14.7.17JunitoiteCaZn2Si2O7 · H2O
14.7.18LarsenitePbZnSiO4
14.7.20HodgkinsoniteMn2+Zn2(SiO4)(OH)2
14.7.21GerstmanniteMnMgZn(SiO4)(OH)2
14.7.22GageiteMn21(Si4O12)2O3(OH)20
14.7.23FranklinfurnaceiteCa2Fe3+Mn32+Mn3+(Zn2Si2O10)(OH)8
51.2.1.1TrimeriteCaMn22+Be3(SiO4)3
51.2.1.2LarsenitePbZnSiO4

Other Names for Esperite

Name in Other Languages:
Dutch:Esperiet
German:Esperit
Italian:Esperite
Spanish:Esperita

Other Information

Bright yellow (SW UV)(Franklin); dull yellow (LW UV)
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

References for Esperite

Reference List:
Palache, Charles, L.H. Bauer & H. Berman (1928), Larsenite, calcium-larsenite and associated minerals at Franklin, NJ: American Mineralogist: 13: 334-340.

Palache, Charles (1935), The Minerals of Franklin and Sterling Hill, Sussex County, New Jersey, USGS Professional Paper 180: 81-82.

Moore, Paul B. & Ribbe, P.H. (1965): "Calcium-larsenite" renamed esperite. American Mineralogist, 50, 1170-1178.

Dunn, Pete J. (1985), The lead silicates from Franklin, New Jersey: occurrence and composition: Mineralogical Magazine: 49: 721-727.

Anthony, Bideaux, Bladh & Nichols (1995), Handbook of Mineralogy, Vol. II: Silicates, Mineral Data Publishing: 225.

Gaines, Richard V., H. Catherine, W. Skinner, Eugene E. Foord, Brian Mason, Abraham Rosenzweig, Vandall T. King (1997), Dana's New Mineralogy : The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, 8th. edition. John Wiley & Sons, New York.

Tait, K., 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.

Internet Links for Esperite

Localities for Esperite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
Bolivia
 
  • Potosí Department
    • Antonio Quijarro Province
[MinRec 21:133]
USA
 
  • New Jersey
    • Sussex Co.
      • Franklin Mining District
        • Franklin
Palache (1935): 81; Dunn( 1995): Pt3: 368.
Steven Phillips
Van King; Chester S. Lemanski, Jr.; Ronald DeBlois.
Palache (1935): 81; Dunn(1995): Pt3: 368.
Mineral and/or Locality  
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