Chabazite Var. Haydenite With Heulandite
Jones Falls Quarries, Baltimore, Baltimore Co., Maryland, USA
Large Cabinet, 16.6 x 9.2 x 3.7 cm
Ex. Philadelphia Academy of Natural Sciences
A large specimen hosting dozens of sharp chabazite crystals showing a golden, iridescent, almost metallic luster. Although small, to about 2mm, the crystals really stand out dramatically because of their sharp geometry and riveting color - more so in person, please note. The earliest reference I found to this quarry was Maryland Geologic Survey, Vol. VIII (1898), as listed on MINDAT, which describes the locality as "A quarry in gneiss located within Baltimore City." This matrix shows the layered gneiss on the backside with the layer of zeolite deposition on top, and so the full environment of the pocket is here. The heulandite is present as almost acicular, oddlooking black sprays laying horizontally on the matrix, much of which is coated with a thin layer of siderite or calcite atop (I think). It is easy to see, from the odd habits of both species, why the specimens from this quarry were thought to be new species at the time: "Haydenite" is Chabazite; and "Beaumontite" is Heulandite, today. Can easily be broken into several study specimens, by the way.