Esperite

{{Infobox mineral

| name = Esperite

| category = Silicate mineral

| boxwidth =

| boxbgcolor =

| image = Esperite under UV light.jpg

| caption = Esperite under ultraviolet light

| formula = PbCa₃Zn₄(SiO₄)₄

| IMAsymbol = Epr{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}

| strunz = 9.AB.15

| system = Monoclinic

| class = Prismatic (2/m)
(same H-M symbol)

| symmetry = P2₁/m

| color = White

| habit = Typically massive

| twinning =

| cleavage = Distinct on [010] and [100] – poor on [101]

| fracture = Conchoidal, brittle

| mohs = 5–5.5

| luster = Vitreous

| refractive = nα = 1.762 nβ = 1.770 nγ = 1.774

| opticalprop = Biaxial (−), 2V measured: 5° to 40°

| birefringence = Max δ = 0.012

| pleochroism =

| streak = White

| gravity = 4.28–4.42

| melt =

| fusibility =

| diagnostic =

| solubility =

| diaphaneity = Subtranslucent to opaque

| other = Brilliant yellow fluorescence under SW UV; kelly green cathodoluminescence.

| references = http://webmineral.com/data/Esperite.shtml Webmineralhttp://www.mindat.org/min-1412.html Mindathttp://www.minsocam.org/msa/Handbook/Esperite.PDF Handbook of Mineralogy

}}

Esperite is a rare complex calcium lead zinc silicate (PbCa₃Zn₄(SiO₄)₄) related to beryllonite and trimerite that used to be called calcium larsenite. {{Clarify|text=It was named in honor of Esper F. Larsen Jr. (1879–1961), petrologist of Harvard University.|reason=Is his middle initial F or S? In some other mineralogy articles (about awards or in references) it is S. Once verified, please correct in all incorrect articles and create a stub under the correct name plus a redirect from the incorrect name to the correct one. Also please consider adding the etymology of the mineral names related to him either in the appropriate Wiktionary articles (such as https://en.m.wiktionary.org/wiki/larsenite) or in a notice on one of WT's discussion pages (https://en.wiktionary.org/wiki/Wiktionary:Discussion_rooms). |date=February 2018}}

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.