This piece is a very fine example of the famed Prehnite casts after Glauberite from the Fanwood traprock quarry in New Jersey! Glistening, less than 1 mm, seafoam green Prehnite crystals cover what were essentially diamond-shaped crystals of Glauberite that were 1 to 2.8 cm in length. The Prehnite casts are so uniform and completely covered the Glauberite that was present. The arrangement of the casts show perfect preservation of the Glauberite form and the casts are nicely isolated on the piece. When you flip the piece over and view the bottom you can barely detect any contacting because the fine Prehnite crystals continue on the underside of the piece! The hollow, crystal lined interiors of the casts are also evident. Prenite casts after Glauberite from this locale are arguably the best of their kind in the world! Ex. Charlie Key and James Zigras personal collections (James grew up collecting in NJ and built a fine collection of unusual NJ minerals, sold or swapped off over the years).