CHAPTER VII. THE FERTILIZER GROUP OF MINERALS 99

GENERAL COMMENTS 99

NITRATES 101 Economic features 101 Geologic features 102

PHOSPHATES 104 Economic features 104 Geologic features 105

PYRITE 107 Economic features 107 Geologic features 108

SULPHUR 109 Economic features 109 Geologic features 110

POTASH 111 Economic features 111 Geologic features 112