Schalenblende from Poland
Contributed by: Michael Crawford
Date: Nov 27th, 2025
Locality: Pomorzany Mine, Gmina Olkusz, Olkusz County, Lesser Poland Voivodeship, Poland (See on Mindat)
Size: 14 cm
Description:
A polished slab of schalenblende from the Pomorzany Mine, Olkusz County, Poland. Schalenblende is not a mineral. It is a rock composed of pale yellow to brown layers that are dominantly sphalerite and possibly some wurtzite, a polymorph of sphalerite, silver galena, and brass marcasite. The name schalenblende comes from the German words schale and blende which translate to shell ore, a reference to its concentric layering, like a cross-section of a shell. The color variation of the sphalerite layers is caused by grain size and iron content. The darker bands contain more iron.
The schalenblende is hosted in the middle Muschelkalk formation (Middle Triassic). The formation includes limestones and evaporites (gypsum, halite, dolomite) and the schalenblende is associated with the dolomitic portion. The ore at Pomorzany is a Mississippi-Valley type deposit in which metal bearing brines are expelled from a deep sedimentary basin into a shallower part of the basin where the fluids get trapped and the metals precipitate. The fine-grained schalenblende layers are believed to have formed by rapid crystallization of a low temperature sulfide gel, a colloidial dispersion of the sphalerite, galena, and marcasite.
The sphalerite fluoresces yellow orange only under longwave UV light. The pale yellow bands fluoresce the brightest yellow orange. The fluorescence becomes darker as the sphalerite darkens due to more iron in the sphalerite. Iron completely quenches the fluorescence from the dark brown sphalerite.
The emission spectrum of the brightest layer is a broad peak with a maximum at 604 nm. As the fluorescence becomes darker, more broad peaks are added to the spectrum. The light brown fluorescence has a second peak around 664 nm. The dark brown fluorescence adds a third broad peak around 570 nm. More analysis is needed to determine if the additional peaks are caused by unknown activators creating new fluorescent peaks, or quenching elements such as iron absorbing light and creating troughs in the spectrum around 640 nm and 585 nm.
Summary of luminescence responses:
Sphalerite (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Orange
- Fluorescence under Longwave (365nm LED) UV light: Orange