I recently watched a segment of This Old House Hour (Newton, Mass. project)which involved installing Milford Pink granite stone to the foundation.
During this segment, Roger Cook mentioned that he wanted to match the original mortar (lime/sand), but it wasn't available.
There is a company in PA that sells that type of mortar (natural hydraulic lime and sand). The mortar also comes in several different colors.
The website for the company is www.limeworks.us
If you have any old house restoration projects that need masonry work, you might want to check out the site.