Icosidodecahedron atop small rhombicosidodecahedron

Icosidodecahedron atop small rhombicosidodecahedron, or idasrid, is a CRF segmentochoron (designated K-4.131 on Richard Klitzing's list). As the name suggests, it consists of an icosidodecahedron and a small rhombicosidodecahedron as bases, connected by 21 octahedra, 30 square pyramids, and 12 pentagonal antiprisms.

It is the second segment of the rectified hexacosichoron in icosahedron-first orientation, the first one being icosahedron atop icosidodecahedron.

Vertex coordinates
The vertices of an icosidodecahedron atop small rhombicosidodecahedron segmentochoron of edge length 1 are given by all permutations of the first three coordinates of: Along with all even permutations of the first three coordinates of:
 * (±(1+$\sqrt{5}$)/2, 0, 0, 1/2)
 * (±(2+$\sqrt{2}$)/2, ±1/2, ±1/2, 0)
 * (±(3+$\sqrt{5}$)/4, ±(1+$\sqrt{5+2√5}$)/4, ±1/2, 1/2)
 * (0, ±(3+$\sqrt{5}$)/4, ±(5+$\sqrt{5}$)/4, 0)
 * (±(1+$\sqrt{7+3√5}$)/4, ±(1+$\sqrt{7+3√5}$)/2, ±(3+$\sqrt{10}$)/4, 0)