ICONOSTASIS

iconostasis, the screen in a greek church which divides the altar and sanctuary from the rest of the church. it is generally attached to the first eastern pier or column and rises to the level of the springing of the vault. the iconostasis or image-bearer has generally three doors, one on each side of the central door, beyond which is the principal altar. the screen is subdivided into four or five tiers, each tier decorated with a series of panels containing representations of the saints: of these only the heads, hands and feet are painted, the bodies being covered with embossed metal work, richly gilded. there is a fine example in the russo-greek chapel, welbeck street, london, which was rebuilt in 1864-1865. icosahedron (gr. [greek: eikosi], twenty, and [greek: hedra], a face or base), in geometry, a solid enclosed by twenty faces. the "regular icosahedron" is one of the platonic solids; the "great icosahedron" is a kepler-poinsot solid; and the "truncated icosahedron" is an archimedean solid (see polyhedron). in crystallography the icosahedron is a possible form, but it has not been observed; it is closely simulated by a combination of the octahedron and pentagonal dodecahedron, which has twenty triangular faces, but only eight are equilateral, the remaining twelve being isosceles (see crystallography).