Wehrite

Wehrite (more commonly spelled wehrlite) is an ultramafic igneous rock made up chiefly of olivine and clinopyroxene, with little or no orthopyroxene. It is a member of the peridotite family, sitting between dunite (nearly all olivine) and clinopyroxenite (nearly all clinopyroxene).

Named after the mineralogist Aloys Wehrle, wehrlite is dark, dense, and rich in iron and magnesium. It commonly occurs as cumulate layers within larger mafic and ultramafic intrusions and also as mantle xenoliths.

It is an uncommon rock seldom seen outside specialist collections and layered-intrusion studies.

Wehrlite forms mainly by the accumulation of olivine and clinopyroxene crystals settling from cooling mafic magma, producing cumulate layers in layered intrusions alongside dunite, pyroxenite, and gabbro. It can also form in the mantle, sometimes by reaction between peridotite and infiltrating clinopyroxene-forming melts.

It occurs as part of ophiolite mantle and lower-crust sequences and as xenoliths carried up by basaltic magmas, recording processes of crystal accumulation and melt-rock interaction at depth.

Wehrlite is a heavy, coarse-grained, dark green-to-greenish-black rock showing granular green olivine together with dark clinopyroxene and little or no orthopyroxene. It often weathers to a brownish rind and may be partly serpentinized.

Hardness is about 6-7. Distinguish wehrlite from lherzolite and harzburgite by the absence of significant orthopyroxene, from dunite by its notable clinopyroxene content, and from clinopyroxenite by its abundant olivine. Microscopic study is often needed for a firm identification.

Wehrlite has little direct commercial use, though wehrlite-bearing layered intrusions and ophiolites can host chromite, nickel, and platinum-group metal mineralization. Serpentinized varieties may yield magnesite or talc.

It has no gemstone or metaphysical tradition. Its main value is scientific, as a record of crystal accumulation and mantle melt-rock reaction within mafic-ultramafic systems.