This is a Polymict breccia, consisting of iron and silicate inclusions mixed with eucritic and diogenitic clasts, which was formed by the disruption and reassembly of a differentiated asteroid. The brecciated surface material was buried under a deep regolith, where it experienced very slow cooling and annealing. Estherville is designated as a transitional 3A/4A metamorphic group." quote by Alan Lang.