|Comments:||For normalized analyses of tweddillite and piemontite from this locality, as well as data for accompanying minerals in the examined thin section, see:|
In my instructional YouTube video tutorial on "Normalizing epidote-group minerals in MS Excel" (https://www.youtube.com/watch?v=IbMLngyz4Cs), the Prabornaz mine "piemontite" analysis I used to illustrate the normalization calculations turned out to be a REE-bearing tweddillite (named as "manganipiemontite-(Sr)" based on the Armbruster et al., 2006 nomenclature).
The sample for this thin section was collected by Pilar Lecumberri-Sanchez (Univ. Arizona) on a field trip to the locality.
|Colour:||in thin section, pleochroic in yellow, orange, red and magenta; similar to and essentially indistinguishable from other Mn-rich members of the epidote group.|
|References:||Frank K. Mazdab collection (see https://www.rockptx.com/fkm-151-to-fkm-175/#FKM-171 for normalized analysis)|
|Mineral Data:||Click here to view Tweddillite data|
|Locality Data:||Click here to view Prabornaz Mine (Praborna Mine), Saint-Marcel, Aosta Valley, Italy|