New Mexico Mineral Symposium — Abstracts

Sterling Hill is one of two mines that make up one of the most renowned mining districts in the world. Who would think that the mineral deposits at the Sterling mine and its sister mine in nearby Franklin would be one of the great geological mysteries known to earth science today? They exist in the Skylands of New Jersey, just an hour from midtown New York.

The Sterling mine is named for William Alexander, Lord Sterling, who owned the property from 1761 to 1776 and attempted to smelt the local ores. Dutch prospectors and the Lenni Lenape Indians probably knew about the Sterling Hill orebody much earlier, which cropped out in plain sight above the Wallkill River.

The Franklin-Sterling Hill mining district represents two centuries of American mining history and technology, mining law, and the earth sciences. It was not until after the perfection of ore-dressing techniques in the early 1800s that mining the deposits became economically feasible.

The ore mined in the district was primarily zinc ore and consisted of the minerals known as:

• zincite, a zinc oxide
• willemite, a zinc silicate
• franklinite, a zinc-iron-manganese oxide.

These three minerals are very rich in zinc and are just a few of the 340+ minerals found in the district. This is about 10% of all those known and constitute a world record for the number of mineral species from a single locality. Yet, zincite and franklinite are nowhere else mined outside the district. Willemite is found in very limited quantities scattered around the globe. Besides the richness of the ore, many of these minerals fluoresce. Again, this is a world record of at least 80 species that are fluorescent—more than any single place on Earth.

The Sterling Hill mine closed for a variety of reasons in 1986. When this mine closed, it meant the end of all underground mining in the State of New Jersey. The Sterling Hill Mining Museum was established in 1989 and opened to the public on August 4, 1990. The Museum has been listed on the Register of Historic Sites since 1991. The Museum continues today as a non-profit foundation. The Museum is also a Mines, Metal, and Men Site.