Labels:circle | crt screen | lamp | lepton | monitor | sky | vase OCR: STRUCTURE Gas Layer: 10 500 km thick Water and Ice Layer: 8,000 km thick Rocky Core: radius 7 ,000 km Composition Uranus has rocky core about the size of Earth, composed of heavy elements, mainly silicon and iron. An icy mantle of water methane and ammonia surrounds the core Like Jupiter and Saturn, Uranus does not have "surface' above the ice mixture of hydrogen, helium and methane extends outward, gradually decreasing in density toward the top of the atmosphere. However, since higher proportion of the planet is rock and ice, Uranus is more dense than its iarger cousins