Looks like iron to me...did you try testing it with RSR 2000 by alpha...Let it sit for a while..If it turns purple its iron

On Wed, May 31, 2017 at 4:16 PM, Mike Marsoun <outerislandstonecare@gmail.com> wrote:
Any ideas on this? Tested for tannin and it's not that. It is spreading. Has been exposed to water.  Suspecting internal rusting. Told the guy I would get a second opinion.
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