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Esperite

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Formula:
PbCa
 
2
Zn
 
3
(SiO
 
4
)
 
3
System:MonoclinicColour: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:Beryllonite, Larsenite


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. Currently in public beta-test.

Classification of Esperite

IMA status:Approved 1964
Strunz 8th edition ID:8/A.03-20
Nickel-Strunz 10th (pending) edition ID:9.AB.15

9 : SILICATES (Germanates)
A : Nesosilicates
B : Nesosilicates without additional anions; cations in [4] and greater coordination
Dana 7th edition ID:51.2.1.3
Dana 8th edition ID:51.2.1.3

51 : NESOSILICATES Insular SiO4 Groups Only
2 : Insular SiO4 Groups Only with cations in [4] as well as >[4]
Hey's CIM Ref.:14.7.19

14 : Silicates not Containing Aluminum
7 : Silicates of Ba, Sr and Zn
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Type Occurrence of Esperite

Type Locality:Parker Mine (Parker shaft), Franklin Mine, Franklin, Franklin Mining District, Sussex Co., New Jersey, USA
General Appearance of Type Material:Massive off-white material in massive ore.
Year of Discovery:1928
Geological Setting of type material:Metamorphosed stratiform zinc-iron-manganese orebody.
Associated Minerals at type locality:
ZinciteWillemiteHardystoniteFrankliniteClinohedrite
Calcite

Physical Properties of Esperite

Lustre: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 (measured):4.28 - 4.42 g/cm3
Density (calculated):4.25 g/cm3

Crystallography of Esperite

Crystal System:Monoclinic
Class (H-M):2/m - Prismatic
Space Group:P21/m {P1 1 21/m} {P21/m} {P1 21/m 1}
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:
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
Maximum Birefringence:δ = 0.012

Chart 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:
PbCa
 
2
Zn
 
3
(SiO
 
4
)
 
3
Simplified for copy/paste:PbCa2Zn3(SiO4)3
Essential elements:Ca, O, Pb, Si, Zn
All elements listed in formula:Ca, O, Pb, Si, Zn
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

Related Minerals - Nickel-Strunz Grouping):

- +
9.AB.05Trimerite
CaMn
2+
2
Be
 
3
(SiO
 
4
)
 
3
9.AB.10Larsenite
PbZnSiO
 
4
9.AB.20Rondorfite
Ca
 
8
Mg(SiO
 
4
)
 
4
Cl
 
2
Related Minerals - Hey's Index Grouping:

- +
14.7.1Sanbornite
Ba
 
2
(Si
 
4
O
 
10
)
14.7.2Krauskopfite
BaSi
 
2
O
 
5
· 3H
 
2
O
14.7.3Walstromite
BaCa
 
2
(Si
 
3
O
 
9
)
14.7.4Macdonaldite
BaCa
 
4
Si
 
16
O
 
36
(OH)
 
2
· 10H
 
2
O
14.7.5Ericssonite
BaMn
2+
2
Fe
3+
 
(Si
 
2
O
 
7
)O(OH)
14.7.6Ericssonite-2O
BaMn
2+
2
Fe
3+
 
(Si
 
2
O
 
7
)O(OH)
14.7.7Gillespite
BaFe
2+
 
[Si
 
4
O
 
10
]
14.7.8Andrémeyerite
BaFe
2+
2
(Si
 
2
O
 
7
)
14.7.9Pellyite
Ba
 
2
Ca(Fe,Mg)
 
2
Si
 
6
O
 
17
14.7.10Taikanite
Sr
 
3
BaMn
2+
2
(Si
 
4
O
 
12
)O
 
2
14.7.11Willemite
Zn
 
2
SiO
 
4
14.7.12Hemimorphite
Zn
 
4
Si
 
2
O
 
7
(OH)
 
2
· H
 
2
O
14.7.13Zincsilite
Zn
 
3
(Si
 
4
O
 
10
)(OH)
 
2
· 4H
 
2
O
14.7.14Hardystonite
Ca
 
2
Zn(Si
 
2
O
 
7
)
14.7.15Petedunnite
Ca(Zn,Mn
2+
 
,Mg,Fe
2+
 
)Si
 
2
O
 
6
14.7.16Clinohedrite
CaZn(SiO
 
4
) · H
 
2
O
14.7.17Junitoite
CaZn
 
2
Si
 
2
O
 
7
· H
 
2
O
14.7.18Larsenite
PbZnSiO
 
4
14.7.20Hodgkinsonite
Mn
2+
 
Zn
 
2
(SiO
 
4
)(OH)
 
2
14.7.21Gerstmannite
MnMgZn(SiO
 
4
)(OH)
 
2
14.7.22Gageite
Mn
 
21
(Si
 
4
O
 
12
)
 
2
O
 
3
(OH)
 
20
14.7.23Franklinfurnaceite
Ca
 
2
Fe
3+
 
Mn
2+
3
Mn
3+
 
(Zn
 
2
Si
 
2
O
 
10
)(OH)
 
8
Related Minerals - Dana Grouping):

- +
51.2.1.1Trimerite
CaMn
2+
2
Be
 
3
(SiO
 
4
)
 
3
51.2.1.2Larsenite
PbZnSiO
 
4

Other Names for Esperite

Synonyms:
Calcium-LarseniteIMA1964-027
Other Languages:
Dutch:Esperiet
German:Esperit
Italian:Esperite
Spanish:Esperita

Other Information

Fluorescence in UV light:Bright yellow (SW UV)(Franklin); dull yellow (LW UV)
Health Warning: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

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  • Raman and XRD data at RRUFF project
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  • Localities for Esperite

    The 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. ? 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.
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