An attempt has been made to relate steatite artifacts to the source of rock from which they were manufactured, using the distribution patterns of rare earth elements. Radiochemical‐ and instrumental‐neutron activation analyses of Shetland steatites suggest that the use of rare earth elements in artifact provenancing may be unreliable. Concentrations of rare earth elements in many Shetland steatites are too low to be measured reliably by a cost effective method. The relative importance of primary igneous and secondary metasomatic processes in controlling steatite rare earth element geochemistry is discussed and geological arguments against the existence of unique rare earth ‘fingerprints’ for steatite are presented.
The contention of Flinn and Moffat (1985) that brecciated serpentinites in the Dalradian of Scotland are komatiites, should not remain undisputed. Their evidence is based on textures preserved in serpentinites which they contend resemble spinifex textures (Nesbitt 1971) found in Archaean ultramafic rocks. Having concluded that komatiites occur in the Shetlands, they proceed to use this as evidence in their far-reaching tectonic reconstructions and comparisons.At the onset, it is important to point out that it is commonly accepted that spinifex textures denote the occurrence of high-magnesian silicate liquids i.e. ultrabasic lava flows. Such flows are quite common in Archaean greenstone belts (e.g. Nesbitt and Sun 1976; Arndt and Nisbet 1982) but are exceedingly rare in post-Archaean rocks. The textures which are found in these rocks (spinifex texture of Nesbitt 1971) have been well documented (e.g. Donaldson 1982). Equally, the textures associated with the regrowth of olivine during the prograde metamorphism of serpentinites are also well documented (Oliver et al. 1972; Evans and Tromsdorff 1974;Collerson et al. 1976;Snoke and Calk 1978). Two types of metamorphic olivine morphology are recorded. The first occurs in tremolite-chlorite assemblages where the olivine is porphyroblastic and the second occurs in talc-carbonate (or sulphide) rocks in which case the olivine is tabular. It is this second type which is commonly mistaken for spinifex texture and it is our contention that the Shetland occurrences fall into this category.Since there is ample documentation of the occurrence of metamorphic 'pseudo-spinifex' olivine, it is surprising that Flinn and Moffat did not discuss the possibility that the textures found in the Shetland serpentinites are secondary. We consider that in view of the important implications resulting from the documentation of komatiites in the Dalradian, such occurrences must be rigorously and critically examined from all viewpoints. This the authors have failed to do, despite the obvious discrepancies between recognized komatiites and the Shetland occurrences (many of which they recognized).
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