Ferrous tourmaline (schorl) in pegmatitic granite from the Khowr Fakkan massif, Semail ophiolite

Tourmaline is a common and locally abundant mineral in the late felsic pegmatitic granites of the Khowr Fakkan massif, United Arab Emirates. X-ray and chemical studies show that tourmalines are Fe-enriched members of the elbaite-schorl series. The infrared spectrum is similar to those of alkali-free tourmalines. The unit cell values are a = 15.98 Å, c = 7.125 Å and V = 1576 Å.