Mineralogical and Chemical Composition of Tourmaline from Najmabad, Gheshlagh,Hired and Maherabad-Khopik, and their relationship with types of mineralization,Eastern Iran

Tourmaline is present as alteration and mineralization at maherabad and khopik cu -au prospecting areas, najrnabad sn-w-au pro specting areas, hired au-sn prospecting area, and within gheshlagh pegmatite dikes. based on x-ray diffraction graphs, maherabad, gheshlagh and hired tourmaline are schorl, but najmab ad and khopik are dravite type. based on chemical composition, all of tourmalines belong to alkali group. the mg/(mg+fe) ratio in gheshlagh tourmaline is 0.21-0.29 , in hired is 0 .32-0.47 and in maherabad is 0 .44-0.5 and in najmabad and khopik are mg/(mg+fe)= 0.55-0.82 . khopik tourmaline contains cons ide rably higher mg ( 1.9-2 .3) compared with the maherabad (mg = 1.4-1.9). the average ti02 content of maherabad tourmaline is 0.35 and khopik is 0.19 . at khopik, deeper portion of the porphyry cu-au is exposed . najmabad tourmaline contains the highest mg (mge 2. 2 ) and gh eshlagh the low est mg (mg=0 .5-0 .7) and highest fe (fe> 1.9-2.3). najmabad tourmaline contains the highest ti02 (0.48%) and other tourmaline contains less than 0.3 % ti02. in general, there is a reverse correlation between cao and na20. gheshlagh has the lowest cao and highest na20. th e cao and na 20 content of tourmaline from hired are very variable