By Steve Chamberlain
Contributing Writer
In an earlier column I introduced the Balmat Mining District in St. Lawrence County and related some talc-mining anecdotes. This column will be devoted to some zinc-mining anecdotes.
The Edwards mine was the first zinc mine opened in the district. Five shafts gave access to an extensive network of adits, drifts and stopes underground along the large ore vein. In 1924, the stope at the end of a drift from the Williams shaft accidentally breached the wall of a 150-foot deep glacial pothole filled with mud and sand. This semi-liquid brown mud squeezed into the mine sort of like a giant Nutella attack. Two houses and an outhouse on the surface were swallowed up. Today, the surface collapse is a 300-foot muddy pond, which is what they thought it was before they inadvertently emptied it into the mine. Although the breach occurred at the 150-foot level, the mud penetrated as deep as the 1100-foot level. Seven cement bulkheads were constructed in various parts of the mine to block further flow. A trammer (mining locomotive) and several ore cars were engulfed by the mud and remain buried underground to this day.
On Dec. 3, 1970 a large cavity was encountered just above the 500-level in the Balmat No. 3 mine. By Dec. 8, the entrance was enlarged enough that miners could crawl 18 feet into the pocket. Although one side of the pocket was lined with interesting specimens of diopside, quartz, hematite, celestine and mountain leather, it was the large, blocky, flawless calcite crystals that were of greatest interest to the miners and the mine geologist. On the floor, near the center of the long pocket was a giant, rose-tinted calcite rhombohedron 28 inches on a side. After estimating its weight at 1,500 pounds, mine captain Perry Caswell and his crew abandoned any hope of removing it whole. They carefully broke it up along cleavage planes into chunks they could handle and brought it out of the mine. One of the large pieces is still preserved at the offices of the St. Lawrence Zinc Company at the Balmat No. 4 mine. Pieces of this large, flawless crystal have been facetted into record-holding calcite gemstones. An 1865-carat calcite gem, cut symmetrically around a twin plane by the late Art Grant of Hannibal, NY, is now in the collection of the Smithsonian Institution and is the largest known facetted calcite.
In the early 1990s, mining at the 2,500-foot level in the Balmat No. 4 mine encountered an unexpected zone of the ore that contained cube-shaped crystals of magnetite, largely embedded in rock salt. These soon became known as the famous cubic magnetite crystals that have ended up in collections and museums across the globe. Not only are cubes an unusual crystal form for the common iron ore, magnetite, these were large groups of mirror-faced crystals and are among the finest specimens of this common mineral found anywhere in the world. The zone was mined through twice, with pauses for collecting. Miners used water hoses to wash the walls and broken rock to dissolve the salt and free the crystals. Thousands of specimens were collected and saved by visiting geologists (including me) and miners. Now, more than a decade later, good cubic magnetite specimens are rare in the marketplace.
One of the ore bodies mined at the Pierrepont mine had a layer of gray, insubstantial rock containing myriad spheres of pyrite. The rock formed the hanging wall in part of the mine and the pyrite tended to fall out onto the miners and the ore-moving vehicles. Those less than an inch in diameter were an inconvenience, but the largest ones, six to 12 inches in diameter were downright dangerous. A hardhat offered little protection. As the little ore trains brought the ore to the surface to be loaded on large trucks and carted off to the Balmat No. 4 mine for processing, many dents, like the craters on the moon, were visible on the locomotives. These were very desirable specimens for mineral collectors, but these too have disappeared from the marketplace, despite thousands having been collected during mining. There is always good stuff to be found by mining in the earth.
