Domestic phosphate deposits

Abstract

Most of the world's phosphate deposits can be grouped into six type*2 1) igneous apatite deposits| 2) marine phosphorites; 3) residual phosphorites j 4) river pebble deposits; 5) phosphatized rock2 and 6) guano. The igneous apatites and marine phosphorites form deposits measurable in millions or billions of tons; the residual deposits are measurable in thousands or millions 5 and the other types generally only in thousands of -.-A ' ". . .