PHOSPHATE MINERALS WITH DISTINCTIVE ATTRIBUTES-CRANDALLITE GROUP

The phosphate deposits on Christmas Island, an Australian territory 1,600 mi west of Perth , W. Australia in the midst of the Pacific ocean have been commercially exploited for fertilizer. Crandallite, CaAl₃ (PO₄)₂(OH)₅ H₂O, is the dominant species in these sediments. It and other low temperature secondary phosphates often occur as crusts, weathering products of mafic igneous or metamorphic rocks and pegmatites as well as in coal beds, mine holes, caves, quarries and in lateritic soils. As they often contain a wide range of trace elements, e.g. Ba, Cd, U, Th and REE, their occurrence/discovery makes them indicator minerals of possible use in exploration for specific elements. Using our Raman, XRD, ICPMS, SEM and microprobe data on crandallite we will offer insights into formation/preservation in these wide geologic and environmental ranges, and some opportunities for extraction of the trace elements.