Esperite is a rare complex lead zinc silicate (PbCa₃Zn₄(SiO₄)₄) that used to be called calcium larsenite. It occurred in the Parker Shaft of the famous Franklin Furnace zinc deposits. It has a white, greasy appearance in daylight and is much prized for its brilliant yellow green fluorescence under shortwave ultraviolet light.

References

• Webmineral
• Mineral galleries
• Mindat