A problem that occurs from time to time with masonry (stonework, brick, manufactured stone veneers) is a white powder or crystal that leaches from the material. This is a result of efflorescene, a natural reaction of minerals in the masonry material that when they come in contact with water result in streaking or leaching marks on the masonry surface. Fortunately, there are products available to treat the problem. Often this leaching is something that will happen initially and then subside overtime. Another precaution that can be taken is to seal the surface with a masonry sealer.