orange staining on thassos slabs in the shower walls

Q.We have installed thassos slab marble on some shower walls in a townhouse in the delray beach florida area. several weeks after the slabs were installed there were some orange/ brown stains that appeared about 12" to 15" off the shower floor.the stains were concentrated in one specific area. we had a marble man extract the stains out and all was good, but then several months later the stains re-appeared. My thinking is that there must be some kind of water leak and what we are seeing is a rust stain that is penatrating through the slabs showing up on the surface. The contractor seems to think that there must have been some kind of void at the seam locations that let water in and caused the problem. If water is setting in the shower pan and was leaching up the wall to create this issue.....wont the lower part of the slab be dis-colored as well? please give me your opinion on what could be causing this problem. I have a site meeting in the AM on 12/29/09 to address this issue so if you can please respond A.S.A.P.

A. Sorry for the delayed response what you may have is an area of the stone that has a high concentration of iron within the stone and it is rusting. I have seen this before with this stone . It could be the caulking or lack of is causing the stone in that area to wick up moisture from the

joint at the floor.If you can send me pics that would be good. Mail@stoneshine.com

Stu Rosen