Diopside (old NYC urban locale!)

Item Description

Preserved specimens of urban geology, especially New York City, are just not that common. This is a very rare large New York City chunk of solid crystallized diopside. The small sugary, tan crystals sparkle in bright light. Two very large crystals are partially exposed on one end. This very rare older example is from the Manhattan Schist from Upper Manhattan. From a museum collection and acquired in 1937. Value of such a rare NYC artifact?