Fibrous foitite from Sebinkarahisar, Giresun Pb-Zn-Cu-(U) mineralized area, northern Turkey

Fibrous foitite occurs in cavities in quartz Veins near Sebinkarahisar town , Giresun mineralized area [Pb-Zn-Cu-(U)], in northern Turkey. Veins of qua rtz + fibrous tourmaline generally cut monzonitic and syenitic rocks. Acicu lar and hairlike light gray crystals of foitite have a mean composition of square(0.43)Na(0.52)Ca(0.07), (Fe1.55Mn0.08Mg0.52Al0.67Ti0.01) Al-6 (BO3)(3 ) Si-6 O-18 (OH,O)(3) (OH)(1). The crystals of this low-temperature tourmal ine radiate from irregular patches of schorl in cavities in quartz veins. E ach fiber is zoned along its length with respect to Fe, Mn, Mg, Ca, Na, K, and P. The fibrous foitite from the Sebinkarahisar area contains higher Mg, Ca and Na contents than that from southern California and Elba.