Calcite from Malmberget, Sweden
Small plate of compact calcite crystals; 7x4x1cm, 59g. Zoned yellow/green fluorescence under shortwave UV light, honey under longwave UV light. From Malmberget, Gällivare, Norrbotten County, Sweden.
For a similar sample, but with only the green fluorescence under shortwave, see this photo on mindat.
The last figure shows the fluorescence spectra under UVC (275nm LED) and UVA (365nm LED) measured for the crystals that best fluoresce yellow and green under UVC. The spectra show composite emissions due to multiple activators, hard to speculate which ones. Both UVA and UVC fluorescence have a complex peak between 500nm and 550nm. Under UVC this first peak has an undulating appearance, which could indicate uranyl emission. A second main peak at around 570nm is only present under UVA and could be due to manganese activation. Not shown in this figure is an intense fluorescence peak at ~350nm, which should be assigned to cerium fluorescence (which could act as coactivator for manganese fluorescence).
Fluorescence under shortwave UV light.
Fluorescence under longwave UV light.
Foto under normal light.
Fluorescence spectra (see top of the page for a description).