On the Phosphate Rock Deposits in the Ryukyu Islands and Principal Components of Phosphate Rockes

Surveying the phosphate rock deposits in the Ryukyu Islands，the writer found that, in the Ryukyu Islands the phosphate rock deposits might be grouped into two main types as follows; (1)Calcarious phosphate rocks.…… deposit in pocket form on hills near seashores．(2)Iron,aluminium phosphate rocks.……deposit in calcium cave. Principal components were determined in order to clarify chemical characteristics of the phosphate rocks in the Ryukyu Islands. Besides the phosphate rocks in the Ryukyu Islands which were mainly investigated，the following rocks and minerals were also tested for a comparative study；（ａ）Phosphate rocks in the South Sea Islands（ｂ）Continental phosphate rocks（ｃ）Apatites in igneous rocks The phosphate rocks in the Ryukyu Islands contain more iron，aluminium and silica than others, and a close correlation exists among these components. This fact suggests that the phosphate rocks contain iron and aluminium as silicate