Uluru is primarily composed of arkose, a type of coarse-grained sandstone that is rich in feldspar minerals. This sedimentary rock formed from sandy sediments deposited in an ancient sea basin about 550 million years ago during the Cambrian period. The sandstone's characteristic reddish hue comes from the oxidation of iron-bearing minerals on its surface. Uluru's structure is notably homogeneous with very little jointing, which has helped preserve it as a prominent inselberg while surrounding softer rocks eroded away. Its feldspar content is unusually high, about 25% or more, which classifies it specifically as arkosic sandstone. The rock's origin is linked to sediment derived from granite sources, and its unique geological composition and weathering processes contribute to its distinct appearance and cultural significance.