Spinel

specimen number:
2262286

location:
Franklin, Sussex Co., New Jersey, USA

description:
A semi lustrous black mostly complete crystal of spinel from this classic locality. The specimen comes with a previous collection data card with an acquisition date of 1967.

The Franklin mining district, located in Sussex County, New Jersey, was a world-famous underground mining center renowned for its massive zinc deposits and an unparalleled abundance of fluorescent mineral species. Geologically, the ore body consists of a highly unusual, stratiform deposit of zinc-iron-manganese oxides and silicates hosted within the Precambrian Franklin Marble sequence. Intense Grenville-age regional metamorphism transformed the original sedimentary and exhalative materials into unique, highly concentrated ore layers dominated by franklinite, willemite, and zincite, completely lacking the standard sulfide minerals typical of most global zinc deposits. Historically, local exploration began in the late 1600s with early colonial prospectors mistaking the iron-rich franklinite for iron ore, but successful commercial development was delayed until advanced metallurgical processing techniques were invented in the mid-nineteenth century. Large-scale industrial underground operations consolidated under the New Jersey Zinc Company in 1897, leading to the sinking of the massive Palmer Shaft, which served as the primary extraction hub for millions of tons of high-grade zinc ore. Heavy production sustained the local economy through both World Wars until the complete structural exhaustion of the complex, keel-shaped ore body forced the permanent cessation of all underground mining operations and the turning off of the pumps in 1954.

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