Strictly speaking, damage caused by pyrite is not isolated to the greater Dublin area and has been recorded worldwide. Pyrite damaged properties have been recorded as far away as Canada and Japan with up to 1000 homes being damaged by pyritic heave in Japan. Canada has a more on-going pyrite problem with an estimated 10,000 buildings having been affected.
So why has pyrite in Ireland only caused problems in the greater Dublin/North Leinster area? Pyrite is an iron sulphide that is a commonly-occurring, but minor constituent of the sedimentary rock group, particularly in mudstones and shales. It is a particular type of pyrite, known as framboidal pyrite, that causes the damage in homes seen in Ireland. This particular type of Pyrite is present in high percentages in the mudstone rock formation called the Tober Culleen formation, which lies around North Dublin extending into North Kildare. Stone from quarries in this area was used as backfill for homes in North County Dublin, Kildare, Meath and parts of Offaly leading to the pyritic heave seen in the groundfloor slabs.
It is the size and characteristics of this formation which has led to such widespread damage across the greater Dublin area. As of now only a few isolated cases have been recorded in other parts of Ireland.
Link to the Geological survey website for people to look this up.