ZINCIAN SPINEL AND STAUROLITE AS GUIDES TO ORE IN THE APPALACHIANS AND SCANDINAVIAN CALEDONIDES

• Main Authors: Cqnadian Mineralogist, Steven, D. Scott
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: zincian spinel; gahnite; zincian staurolite; Appalachians; Scandinavian Caledonides. electron- microprobe; Bleikvassli; Norway
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.598.3673; http://rruff.info/doclib/cm/vol24/CM24_147.pdf

Zincian spinel or gahnite (Zn,Fe, Mg)Al2Oa occurs in metamorphosed massive-sulfide deposits, aluminous metasediments, pegmatites, quartz veins, and metamor-phosed oxide-silicate deposits in at least forty localities within the Appalachians and Scandinavian Caledonides. Most occurrences are associated with metamorphosed massive-sulfide deposits, in which gahnite is considered to form predominantly by desulfurization reactions involv-ing a member of the system Fe-S-O and either sphalerire and garnet or sphalerite and alurninosilicate. Spinel in quartz veins and pegmatites is thought to be a product of metamorphic-hydrothermal solutions and magmatic processes, respectively. Spinel in aluminous metasediments was probably derived from the metamorphism of metal-liferous shales, in which rocks Zn may originally have been Iinked to organic material. Although gahnite in some sul-fide deposits coexists with zincian staurolite, textural ev! dence suggests that staurolite did not act as a precursor to spinel. The high Zn content in staurolite is likely the result of desulfurization reactions. Staurolite from the Bleikvassli deposit (Norway) contains up to 8.77 wt.Vo ZnO and is thought to be the most Zn-rich yet recorded. Both gahnite and staurolite are most Zn-rich where associated with sul-fides and may constitute an exploration guide for massive-sulfide deposits in metamorphosed terranes.