The astrobinary consists of two axially aligned grains containing clusters of twinned octahedral nanocrystals of high density. (a) and (b) Volume-rendered images showing the astrobinary and twinned nanocrystals, respectively. Red, green, and blue arrows in panel (b) denote the X-, Y-, and Z-axes. (c) Close-up of twinned octahedra (larger arrow in panel (b)) with orthogonal elongated axes (∼20 nm long). (d) Close-up of a small octahedral nanocrystal (small arrow in panel (b)) before its twinning with a crystal to the right. The green cube is the voxel size 15.753 nm3. (e) Maximum intensity projection close-up of the nanocrystal cluster in the lower grain. Bright linear features running across the nanocrystals are primarily phase contrast that appears at their edges, overlapping bulk absorption contrast. A protrusion at the top right is a portion of its neighbors. The volume is 157.50 × 173.25 × 425.25 nm3 for panels (a) and (b), 47.25 × 63 × 63 nm3 for panel (c), and 94.50 × 141.75 × 141.75 nm3 for panel (e).