Will you cut mortises in the posts? If so, I don't think you will have any problems. Our local granite shop makes a fence just like that out of Elberton granite.
I would most concerned about kids climbing on it and possibly breaking the horizontal piece.
Contractor Talk - Professional Construction and Remodeling Forum
A forum community dedicated to professional construction and remodeling contractors. Come join the discussion about the industry, trades, safety, projects, finishing, tools, machinery, styles, scales, reviews, accessories, classifieds, and more!