『Abstract
　A phosphatic alteration rind is described comprising a leucophosphite crust above a phosphatised substrate of serpentinized peridotite from an exceptionally isolated location experiencing high rainfall conditions. The formation of the rind is intimately linked to the deposition and subsequent leaching of guano associated with the high concentration of seabirds that nest on the islands and its transformation into a ‘weathering rind’. The favoured pathway into the substrate appears to be along a pre-existing microfracture network, via the alteration of its carbonate infill into soluble apatite. This apatite is only retained within the protected environment of the microfracture network. Surrounding the network, there is evidence of the continued inward migration of the leachate into the surrounding peridotite resulting in its gradual phosphatisation in the form of a ‘halo’ around individual fractures. On the exposed rock surfaces, the consequence of the reaction between the guano leachate and the underlying substrate is its transformation into a ‘weathering rind’ composed principally of leucophosphite. It appears that the widespread formation of a phosphate crust is constrained by continual surface loss in a high energy, salt-rich maritime environment exposed to extensive overwash, wave attack and ultimately erosion.

Keywords: Leucophosphite; Guano; Weathering; Selective extraction』

Introduction
Location, geology and general description of the archipelago
Sampling and analysis
Results and discussion
　Mineralogical investigations
　Element partitioning
　　Sample SPSP1
Interpretation and conclusions
Acknowledgments
References