Each of these 2.6 LB. stones measuring 5" wide, 4" tall and 3" deep are cast with a "super concrete" recipe containing cement, course limestone, sand, metakaolin, plasticizer and water. It is super strong and will last outdoors. The engraved portions of the rocks are colored by mixing dry iron oxide pigments, a cement type material called "scrafino" combined with an acrylic co polymer. This stuff is durable enough to withstand the harshest of weather and will not peel off or fade like paint tends to do in time. Finally, the rocks are sealed with a thick layer of acrylic sealer which gives the rock a semi gloss appearance.