the forumad ophiolite in the northwestern part of the sabzevar region has embraced the largedepleted harzburgites and dunitic bodies associated with podiform chromitites. in some deposits, chromitegrains have segregated as nodules. the stretched shape along with high cr2o3 and tio2 contents are thecharacteristics of the nodules. compared to the other tethyan nodular chromites, the forumad nodul...

Compositional fields for spinels from a wide variety of mafic– a wide range of conditions from mafic and ultramafic ultramafic igneous rock types and tectonic environments have been magmas and, in the case of chromites, are often among determined from a global database of over 26 000 analyses. the first phases to crystallize. They also exhibit a wide These fields are defined using contoured dat...

By examining the minor and trace element contents of chromites from three intrusions—the Bushveld Complex (South Africa), Stillwater (USA), Great Dyke (Zimbabwe)—and comparing these chromite compositions with those magmas which they could have formed (komatiites picrites) we conclude that ( i) variations in Ti, V, Sc, Ga across stratigraphy individual layers do not support model magma mixing le...

Introduction: Igneous and metamorphic rocks commonly contain a mineral assemblage that allows oxygen fugacity to be calculated or constrained such as FeTi oxides, olivine-opx-spinel, or some other oxybarometer [1]. Some rocks, however, contain a limited mineral assemblage and do not provide constraints on fO2 using mineral equilibria. Good examples of the latter are orthopyroxenites or dunites,...

MINERALOGICAL and physical characteristics of natural chromites from Oman ophiolites have been recently investigated using M6ssbauer spectrocopy (MS), X-ray diffraction (XRD) and Scanning electron microscopy (SEM) by Al-Alawi et al. (1996). From the MS analysis together with the SEM data, they derived the chemical formula for specimens collected from two separate chromite deposits named Tawiyah...