These are hard calcium deposits he could be from the water or could be from the mortar that was used to set the tile. You could try scraping it away and try and mild acid and repolishing the travertine if it’s polished. My guess is the same installation failure and it probably needs to be replaced. Additional note I would check the water to see how hard water is. The calcium deposit could be coming from the water.Sent from my iPadDiamond Stone & Tile CareBarry RadutaThanks again,My situation is that I want to get a sharp chisel and hammer at an angle and try and break it loose, but I am worried about cracking the travertine. You can see in the photo that the mass follows the grout lines. If I use an acid it will etch out the tiles. Is this a job for me or a demo team and a tile installer?Hello Partners.Thank you in advance for any help you can share with me. I was called by a prospect to evaluate their travertine floor in the master bath and when I was measuring the floor I noticed this problem growing on their shower floor. This seems to be a salt (or some substance ) that is up to 3 inches wide and a 1/4 to 3/8 inch high. Can efflorescence turn into a hard mass like this considering this shower is used every day? Also, there is really not an evidence of mold growing elsewhere in the shower.Visit list archives, subscribe, unsubscribe or change your subscription preferences: http://stoneandtilepros.simplelists.com/sccpartners Start a new conversation (thread): sccpartners@stoneandtilepros.simplelists.com <IMG_2831.JPG>Visit list archives, subscribe, unsubscribe or change your subscription preferences: http://stoneandtilepros.simplelists.com/sccpartners Start a new conversation (thread): sccpartners@stoneandtilepros.simplelists.com