Esperite

Esperite is a rare complex calcium lead zinc silicate (PbCa₃Zn₄(SiO₄)₄) related to beryllonite and trimerite that used to be called calcium larsenite. It was named in honor of Esper F. Larsen Jr. (1879–1961), petrologist of Harvard University.^{[clarification needed]}

Esperite has a white, greasy appearance in daylight and is much prized for its brilliant yellow green fluorescence under shortwave ultraviolet light. It is found in association with calcite, franklinite, willemite, hardystonite and clinohedrite. It has also been found as prismatic crystals up to 1 mm in length at the El Dragon Mine, Potosi, Bolivia in association with allophane, chalcomenite, clinochalcomenite and barite.

References

1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
2. http://webmineral.com/data/Esperite.shtml Webmineral
3. http://www.mindat.org/min-1412.html Mindat
4. http://www.minsocam.org/msa/Handbook/Esperite.PDF Handbook of Mineralogy

• Mineral galleries
• Pete Dunn, Franklin and Sterling Hill, New Jersey: the world's most magnificent mineral deposits, part 3 p. 368 (1995)
• G. Grundmann, et al.: The El Dragon Mine, Potosi Bolivia, Mineralogical Record v.21 #2 p. 142 (1990)
• Anthony et al., Handbook of Mineralogy, Vol. 2 (silicates) part 1 p. 225 (1995)

Robbins, Manuel: Fluorescence Gems and Minerals under Ultraviolet Light Geoscience Press pp 50–51,243 (1994)