Great heptagrammic retroprism

The great heptagrammic retroprism, or gisharp, also called the great heptagrammic crossed antiprism or simply the heptagrammic crossed antiprism, is a prismatic uniform polyhedron. It consists of 14 triangles and 2 great heptagrams. Each vertex joins one great heptagram and three triangles. As the name suggests, it is a crossed antiprism based on a great heptagram, treated as a 7/4-gon rather than 7/3.

Vertex coordinates
The vertices of a great heptagrammic retroprism, centered at the origin and with edge length 2sin(3π/7), are given by: where $$H=\sqrt{\frac{1-2\cos\frac{3\pi}7}{2-2\cos\frac{3\pi}7}}\sin\frac{3\pi}7.$$
 * $$\left(1,\,0,\,±H\right),$$
 * $$\left(\cos\left(\frac{2\pi}7\right),\,±\sin\left(\frac{2\pi}7\right),\,±H\right),$$
 * $$\left(\cos\left(\frac{4\pi}7\right),\,±\sin\left(\frac{4\pi}7\right),\,±H\right),$$
 * $$\left(\cos\left(\frac{6\pi}7\right),\,±\sin\left(\frac{6\pi}7\right),\,±H\right),$$