which, upon contact with water or water vapor, expand, exacerbating the exfoliation of the stone, sending shards careening onto the skulls of passersby...
No evidence of shardification or human remains in vicinity. Indeed all mica-infested areas clean and tidy, although it is possible that is devious terrorist plot. Nice delam on 3' x 4" lintel over door, but that isolated piece is slathered in "brownstone" paint.
If you keep exacerbating yourself you'll go blind. Christopher