I had a local stoneyard produce some nice cut stone to cover the brick around my fireplace, and they recommended that I use mortar to adhere them to the old brick.  I just want to know if I can use a mastic for the job.  The stones are cut on five sides so they stack nicely.  There will be some heat that comes out from the “burning glass” fireplace so I don’t know if that will affect the mastic…..

Frank