(n.) A rock made of sand more or less firmly united. Common or siliceous sandstone consists mainly of quartz sand.

aa abyssal rock basalt bedrock block lava brash breccia conglomerate crag druid stone festooned pahoehoe gneiss granite igneous rock lava limestone living rock magma mantlerock metamorphic rock monolith pahoehoe pillow lava porphyry pudding stone regolith rock ropy lava rubble rubblestone sarsen schist scoria scree sedimentary rock shelly pahoehoe stone talus tufa tuff