I suggest to expand the stone type map to include the entire continent, rather than just the Riverlands. This would create a better overview for projects on the borders of regions and the relations between them.
I think an even better way to showcase stone types would be to only indicate possible sources of types of stone, rather than creating blanket areas for material use. This way there will be "empty" areas, where stone should be scarcer since it can't be quarried locally, while highlighting areas that have an abundance in stone.
I made a quick mockup of what I mean:
It's a quick sketch of the three most prominent hills and mountain ranges from which stone is mined, as well as the rivers that should have enough clay to make bricks with. It can also feature prominent quarries where specific stones are mined, such as marbles. I randomly placed the marker for Blue Veined Marble somewhere in the Vale.
There are a lot less hard borders this way, making it clearer what the ratio of different stones should be in border projects or projects with no natural stone within it's borders.
It also gives an indication of areas where current or proposed stone types might clash with what would be realistic based on nearby resources or a lack thereoff, which might portray the need for additional hills where stone can be quarried. An example would be the pink stone of Maidenpool. Did they import stone from the upper Red Fork and if so, why don't other locations along the Trident, or is there a quarry nearby where different pinkish stone comes from and if so, does it come from the Vale, Crackclaw point or south-west of the city?
