Prehnite Cast After Anhydrite
Cabinet, 13.7 x 12.0 x 4.5 cm
Prospect Park Quarry, Prospect Park, Passaic Co., New Jersey, USA
This is a large plate covered in a jackstraw arrangement of slender fingers, to 7 cm in length, of translucent, light apple-green, prehnite. Most of the prehnite here is of the finger habit, where it formed as a thick overgrowth on earlier anhydrite. The largest crystal, though, shows the straight lines of the anhydrite replacement more closely and preserves the original crystal habit with better fidelity. There is some kind of oriented coating of another mineral on the backs of the crystals, that reduces the light coming through, and hence the color a little bit, but the prehnites facing the viewing angle are lustrous and apple-green and the piece as a whole is impactful. As with many larger pieces from this pocket, several fingers are broken, but here they are minimal to the display view and picked down to their roots, so they do not detract much except on close inspection and from the side views (though I mention it to explain the lower apparent price here for a very large cabinet piece, to be fair about amortizing the values). Damage to the tips of a few little fingers is insignificant when the whole specimen is taken in context. The bottom of the specimen exhibits clear evidence of hollow casts after anhydrite, upon which the prehnite formed. This is a major matrix piece, and large for having no repairs by any historical standard here. Dramatic and 3-dimensional!