A small peridotite massif (~5 km x ~ 0.6 km) crops out on the Northern flank of the Jabal Nakhl close to the Taww oasis in the Northern Oman mountains. It rests directly on the autochthonous and is over-thrusted by the Hawasina nappes, which contrasts with the structural position of the Semail ophiolite. The lack of pervasive high-temperature mylonitization and the absence of a metamorphic sole at its base is a distinctive feature of the Taww massif which appears more structurally linked to the autochthonous than to the allochthonous units. Its exhumation was synchronous with the one of the autochthonous with no relative displacement during or after this event.The Taww peridotite is characterized by the abundance of clinopyroxene (Cpx); its modal composition is transitional between Cpx-harzburgite and lherzolite (> 5% Cpx). Cpx is associated in clusters with orthopyroxene porphyroclasts. This texture and mineral composition of the Taww peridotite are consistent with residues left after a moderate degree of partial melting of a fertile peridotite. The Taww peridotite has a mineralogical and chemical composition contrasting with that of the Semail peridotites made essentially of harzburgite generally devoid of Cpx and with trace element patterns pointing to melt-rock reaction. When present in the Semail harzburgite, Cpx is mostly interstitial and attributable to melt (+/− hydrous fluids) percolation and crystallization, an origin that can be excluded in the case of Taww Cpx.The Semail ophiolite evolved in a highly productive magmatic environment, likely a fast spreading centre. Conversely, the Taww peridotite is closer to peridotites from highly stretched continental margins or post-orogenic subcontinental mantle. The Taww massif clearly experienced a different emplacement, partial melting, melt migration and melt-rock interaction history than the Semail ophiolite. Whatever its origin, which remains puzzling, the Taww peridotite does not seem to belong to the same obducted units as the Semail and Hawasina nappes.