I’ve seen this a few times before where some cracked or damaged tiles were replaced after the initial installation. The installer had used a setting material not suited for natural stone. 
Recently I replaced a marble backsplash tile that was put in with liquid nail. Unbelievable!! and was union on new high end condos in Boston. Must have been behind schedule. 

Chris Santospago 
Restoration by Design Stone 

Sent from my iPhone

On Sep 23, 2018, at 6:58 AM, Randy Frye <rfrye6@gmail.com> wrote:

Your thought:  “I’m thinking that maybe the tiles were factory impregnated with phenolic resin and the resin has turned in a few places. "

I think your right. Especially since whatever is happening is not carrying over to the next tile. Its an indicator its nothing with the underneath touching the tile like thin set  or being applies to the face to clean them. May look into replacing the individual tiles if possible. Good Luck


On Sep 22, 2018, at 1:43 PM, Bstandish <bstandish@facspecs.com> wrote:

Hi Partners. I told a homeowner that I would come out to do a test on some granite that has been stained. There are intermittent tiles that have become yellow although those around them have not. The stains do not carry to the tiles around them. Has anyone experienced this or have any idea what is going on?  I have never seen this before. I’m thinking that maybe the tiles were factory impregnated with phenolic resin and the resin has turned in a few places.
Thanks for any insight
B


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Baird Standish
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Facility Specialists, LLC
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