Iridophores are structures that produce iridescent colors with a metallic sheen. Exterior colours were limited to Ocean Race Blue Metallic or Electric Silver Metallic. They were Pewter metallic and Dark Copper metallic. Mocha Steel Metallic, Green Steel Metallic, and Ice Blue Metallic. Most alloys of arsenic with metals lack metallic or semimetallic conductivity. The Graphite Metallic color is discontinued. Plumage is typically dark with a metallic sheen. Non Metallic and Paint to Sample Metallic colours. Aluminium oxide is responsible for the resistance of metallic aluminium to weathering. Ceramic and metallic diaphragms are used. This is contrary to the behavior of metallic substances such as copper. Spiral-wound gaskets comprise a mix of metallic and filler material. Native titanium (pure metallic) is very rare. The pottery was polychromic, with geometric decorations and applications of metallic ornaments. "Solar Red" and a fourth in 148B "Acacia Green Metallic".