[Rockhounds] As Notre Dame is being rebuilt, replacement stones that may be suitable are now going through laboratory testing

[Kreigh Tomaszewski]

One of the challenges is finding new quarries or bringing decommissioned
ones back into service to provide the large quantities needed

By mid-2021, preliminary scientific work to replace the destroyed masonry
bricks from the devastating Notre Dame fire on April 15-16, 2019, should be
complete. Appropriate materials have been sought since July 2020, and
laboratory tests have now begun in January 2021.

The challenge is not only to locate varieties for reconstruction that are
as close as possible in appearance and properties to the old materials.
This time, it is also a question of providing large quantities, far more
than have been continuously demanded to date for the preservation of the
structure.

The starting point for this stone search is actually favorable: In the past
50 years, in the course of the continuous restoration, detailed analyses
had been carried out to determine from which quarries under Paris and from
the nearby surroundings the limestones for the respective construction
phases from 1163 to 1345 and for the major restoration from 1844 to 1864
had come.

In the meantime, 30 active quarries and 20 out-of-use quarries have been
identified that could be suitable for the supplies now needed, the trade
journal Pierre Actual wrote in an article in its January issue.

https://www.stone-ideas.com/86373/notre-dame-replacement-stones/