The wavy black forms signal a symplectitic texture. Symplectites appear in metals, minerals and other materials. They are intergrowths of two or more constituents and appear in a variety of configurations. They may be considered a disequilibrium textural feature. The different phases may form from: a single phase that becomes unstable from a pressure or temperature change (e.g. exsolution); a reaction between adjacent materials; the introduction of a reactive fluid.
In this dunitic diogenite the dark mineral is very likely chromite, according to a researcher who has worked on similar meteorites.