Of course, one sees growth of curved carbonate multicrystals, such as
saddle-shaped dolomite or calcite or aragonite forming helictites in near-
surface environments. I have seen para-amphibolites with large sprays of
randomly oriented actinolite or hornblende but not forming curved shapes.
If the crystals are small, I wonder if they could have grown around a
previous porphyroblast, say calcite or during retrogression of cpx.
Chlorite often forms rounded to curved sheaths when pseudomorphing garnet
or orthopyroxene. What rock type and what assemblage do you have with this
feature, and is there any distinctive mineral in the cores of the circles?
Can any member of our group provide an explanation as to why
>amphibole in a metamorphic rock (or, for that matter kyanite, or any
>other normally straight elongate mineral) might instead grow as
>randomly-oriented curved crystals? (Some of the amphibole curves so
>much that groups of crystals forms circles or perhaps spirals in a
>This does not look to me to be a product of
>growth-during-deformation. The overall distribution of the amphibole
>crystals is random, although that texture has been overprinted a
>little by the development of a later foliation.
>I have a vague vague recollection that this texture might be related
>to the speed of mineral growth(?), but I haven't been able to turn up
>Thanks in advance,
>Senior Lecturer - metamorphic petrology
>School of Earth Sciences
>Victoria University of Wellington
>P.O. Box 600
>Wellington, New Zealand
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