This specimen is an excellent example of building with the materials at hand. It is a piece of concrete, collected from the Trotter Dump, Franklin, New Jersey. It likely originated as part of the foundation for one of the Franklin Mine buildings, and is composed of waste sand and mine tailings containing some of our favorite fluorescent Franklin minerals. Waste material from the Franklin Mine was often used for construction purposes. Looking quite ordinary under visible light, this piece of concrete shows a spectacular multi-colored fluorescent response under short wave UV, dominated by the green of willemite, red/orange of calcite, and blue fluorescing hardystonite. The size of this piece is 5.44 x 3.48 x 1.93 inches, and it weighs 638 grams. This specimen is literally a piece of Franklin history!
The photograph above shows the broken surface of the concrete under short wave UV (254 nm). Pieces of calcite fluoresce red/orange, willemite is green, and blue fluorescent hardystonite is clearly visible at the left edge.
Visible light photograph of same side of the specimen as shown in the first picture.
The reverse side of the specimen is shown above under short wave UV (254 nm). This side features a sawn surface and the same mineral assemblage.
The sawn surface of the specimen is shown under visible light.