TOPIC: Unusual Deposits on ceramic tile

These photos show what appears to be calcium deposits which have `popped up``on ceramic tile located on an office floor which had a roof leak and a mold problem. They only appeared on white tiles but not on other coloured tiles in the same office building.
The owner though maybe there was a moisture intrusion from below and dug down 4 ft but there was no water present.

Has anyone seen anything like this. Help!

need more than a visual inspection to determine the kind of deposits on the tile, this will have to be sent to a lab for documentation of the kind of material that is.