Reaction between the silica thus released and the serpentinite with which it came in contact was thought to have caused asbestification.[…]On the Makinyambu property in particular, asbestification of the centre has been restricted to a few well-defined blocks where dynamic action was probably greatest rather than being uniformly operative throughout the mass.[…]The other main form of alteration, asbestification, is considered as specifically a result of the operation of shearing stress under the same general conditions.[…]Although the structure is complicated by a series of block-faults, there seems little possibility here that serpentinization and asbestification resulted from ground-water action.
Source: wiktionary