Phosphorites from NW Jordan were examined petrographically and chemically. Their mineralogy is basically simple and includes apatite (francolite), carbonate (mainly micritic calcite), some dolomite, and minor clay minerals and organic matter. These mineral phases control the chemistry. The phosphorite deposits are made up of several depositional cycles that indicate shallowing and show decreasing particle size. They are believed to have formed by authigenic precipitation followed by reworking and redeposition in the inner parts of the basin, where only minor amounts of micrite and clay were being deposited.