Background: Over the past century plus, The New York Mineralogical Club has amassed a huge collection of minerals, with donated specimens, purchased, collected, and bartered for by its members. The minerals of New York City (NYC) were formed at great depth in the earth during and after primary high grade metamorphism of their bedrock hosts. Various native metamorphic rocks that underlie the city, including marble, quartzite, schist, gneiss, granofels, and amphibolite, show the effects of numerous phases of mineralization. Commonly developed during metamorphic recrystallization, metasomatic reactions, along faults and within contact zones of crosscutting igneous rocks, these historic mineral specimens were collected (many over a hundred years ago) during construction of the city's infrastructure. They are a legacy to the natural beauty of a now overdeveloped cosmopolitan area.

Looking down the crowded streets and avoiding speeding cabs, we can lose track of the slow, inexorable geologic development of our area or of the effects of glaciers that recently (less than 12,000 years ago) honed the earth's surface. In NYC, all of the bedrock units now exposed at the earth's surface, were subjected to two episodes of high pressures and great, fusing temperatures, formerly existing in the depth range of 25-40 km (~15-25 miles). The crystalline bedrock that forms the solid underpinning of New York's magnificent skyline has been exhumed from these great formative depths. Controlled by the bulk chemistry of the host rocks and the reactive chemical nutrients of penetrating active fluids, mineralization has left a trail marker of changed geological conditions. They have resulted in formation and subsequent erosion of the Appalachian mountains during roughly 1.1 Billion years of protracted Proterozoic and Paleozoic mountain building.

Geologists use mineral assemblages in rocks of the earth's crust in much the same way that a race-car driver (or average NYC motorist, for that matter) would use an instrument cluster in their vehicle to gauge performance. We, as geologists, use the textures- and minerals in rocks as "gauges" to estimate past variations in strain patterns and changing crustal position in an effort to reconstruct ancient mountain building events. Comments below on the individual specimens are attached for educational purposes only and are the result of carefully examining the specimens within the context of our decades of field examination of the bedrock of NYC. The captions are written and copyrighted by Dr. Charles Merguerian of Duke Geological Laboratory and Hofstra University and are available for any not-for-profit educational purpose possible. We are indebted to the New York Mineralogical Club and the American Museum of Natural History for permission to examine, photograph, and "electronically" publish these images for all mineral collectors, and admirers of natural beauty the world round to enjoy.

Technical details:*Olympus OM-2 camera with 50mm f 3.5 Macro lens using Ektachrome Tungsten ASA 160 color slide film. Kodak processed slide images scanned at 600 dpi and then converted using PhotoShop into .jpg images. U.S. Jefferson nickel added for purpose of scale. We are indebted to Joseph Peters, Glenn Curtis, and John Betts for permissions and direct assistance in completing this foray into the archives of the American Museum of Natural History. These images are intended for non-commercial enjoyment only. All rights reserved [© 2000] by the New York Mineralogical Club and Duke Geological Laboratory. Photographed, in March 1998, by Charles Merguerian at the American Museum of Natural History.

Attribution: Comments on the individual specimens are attached for educational purposes only. The captions are written and copyrighted by Dr. Charles Merguerian of Duke Geological Laboratory and Hofstra University and are available for any not-for-profit educational purpose. We are indebted to the New York Mineralogical Club and the American Museum of Natural History for permission to examine, photograph, and electronically publish these images.