The iron silica sandstone is mainly distributed in the westnorth of Hsiaomen Elementary School,part of it develops in the east of the islet, sporadically distributed in blocks. The grain size of silica sand in the rock block is uniform, about 2 mmeven finer,the cementitious rock is limonite. Because the rock is so solid, residents often collect it as a material for building windbreakshouse walls. As a result, the entire rock formation is damaged very seriously. When exposed to the earth surface, the iron silica sandstone is oxidizedthe limonite is weatheredpeeled off, leaving silica sand to cover the entire area. This specimen was collected from Hsiaomen Islet.