Mines and mineral localities

More than a century has passed since minerals from this area were first described. Few of the earlier papers gave details of the localities and the mode of occurrence of the minerals, and changing conditions of mining operations have made obsolete some of the locality names formerly used. In order to make clear many of the references to such localities a brief statement of the mining operations in the district seems necessary.

The original outcrop at Franklin (named Franklin Furnace until 1918), in the township of Hardyston, was on a small eminence named at an early date Mine Hill. (See plate 1.) [but warning: large file] The outcrop, half a mile long, of the western leg of the ore body was first opened by cuts and inclined shafts worked independently. Such were the Hamburg mine, the Trotter mine, and the Dingdong shaft. In 1852 the eastern leg of the ore body was discovered in what was then called the Buckwheat field. The pitching synclinal connection of the two legs was laid bare much later and came to be known as the Buckwheat mine or Southwest opening, and still later, when worked by stripping, as the Buckwheat open cut. The Taylor mine was on the eastern leg of the ore body near the north end of the outcrop. About 1890 diamond drilling on the east side of Mine Hill proved the northward extension underground of the eastern leg of the ore body, which was reached by sinking the vertical Parker shaft, nearly 1,000 feet deep. In 1897 all the properties at Mine Hill were consolidated under the management of the present New Jersey Zinc Company and a new method of mining was established.

The Palmer shaft, an incline 1,500 feet long sunk in the footwall gneiss near the north end of the western outcrop of the ore body, was driven to the bottom of the syncline, and through it all ore is hoisted to a single concentrating plant. The ore is removed by a system of stope slicing and topslicing introduced by R. M. Catlin and described in a paper by Haight and Tillson (218), engineers of the mine. The ore as it reaches the shaft head is thrown on a grizzly, and the oversize passes on, after being washed, to a circular picking table, where waste is removed by several men. Specimens found on the picking table may therefore have come from any part of the mine, and only specimens actually found in the mine and located by the finder can be assigned to any definite locality other than merely Franklin. Many exact locations in the mine are given, however, in recent papers. Localities are designated by the depth and by pillar numbers, north or south of an east-west line through the Palmer shaft.

As pillars and slices are emptied of ore they are filled with waste, part of which is tailings and waste from the picking table but much more of which is rock broken from the mass of limestone between the two legs of the ore body and conveyed into the mine by chutes. All the older localities on and about Mine Hill that were within the original outcrops of the ore body, including all the older mines, have been obliterated by the later operations.

At Sterling Hill, in the township of Sparta, where the ore originally cropped out, as at Franklin, in an eastern and a western leg or "vein", were the earliest authentically known workings, the Lord Stirling pits. The space between the two legs of the ore body was worked for calamine by two open-cut mines called the Passaic and the Noble. Work on the main ore body ceased about 1900, and the property was idle for a time. About 1913 a shaft was sunk and extensive underground development was begun. At Sterling Hill also there is a picking table, on which specimens are sometimes found. Caving operations to obtain filling material have obliterated the evidence of earlier mining in considerable parts of the Sterling Hill area, as at Franklin.

The following explanation will help renders to understand the references to localities, indicated by numbers on plate 1, that are now for the most part no longer in existence. The localities are numbered serially in geographic order from north to south.

1.	The Palmer shaft is an inclined shaft, sunk in the footwall gneiss, through which all hoisting of ore from the mine has been done since 1909.
2.	The Parker shaft was a vertical shaft, sunk through the limestone, from which a crosscut was run at a depth of about 1,000 feet to intersect the ore body. Somewhere, probably near the ore, this crosscut encountered abundant pegmatite and a pneumatolytic deposit of extraordinary complexity, whose form, however, is unknown and whose nature is known only from specimens collected on the dump. The minerals found include native lead and copper, clinohedrite, roeblingite, hancockite, glaucochroite, franklinite, leucophoenicite, cyprine, nasonite, axinite, datolite, willemite in exceptional crystals, barite, rhodonite, garnet, phlogopite, and many others. The Parker shaft was for a long time one of the chief openings of the mine, and minerals brought out through it may have come from almost anywhere in a considerable underground area.
3.	The Hamburg mine was a small open pit on the outcrop, in which were found transverse veins containing sussexite, pyrochroite, greenockite, rhodochrosite, and remarkable radiate masses of fibrous willemite.
4.	The Trotter mine was an inclined shaft in which the ore body was cut by numerous dikes of pegmatite containing fine microcline, thorite, zircon, titanite, and allanite. Notable contact effects were revealed, with the development of much garnet, pyroxene, rhodonite, and biotite and its alteration to caswellite and axinite. At the depth of 340 feet the shaft penetrated a pneumatolytic deposit consisting of yellow sphalerite, purple fluorite, niccolite, and chloanthite, the niccolite being partly altered to desaulesite. Secondary veins of sphalerite and recrystallizations of the primary minerals are common in specimens that were found on the dump from the Trotter shaft.
5.	Double Rock was the outcrop, no longer in existence, of a large mass of pegmatite near the Trotter shaft, where abundant large crystals of garnet and pyroxene were found in the adjacent limestone.
6.	In the west wall of the Buckwheat open cut was exposed a veinlike mass of gray dolomite containing in its cavities crystals of quartz, dolomite, albite, sphalerite, pyrite, millerite, and goethite.
7.	The tunnel to the Wallkill River from the Buckwheat open cut yielded the unique cubical crystals of gahnite described by Brush (100).
8.	In the Buckwheat mine (Buckwheat open cut or Southwest opening) the ore body was exposed by stripping of the overlying limestone in the pitching trough. Both the ore and the stripping yielded many interesting minerals contained chiefly in transverse secondary veins of great variety. (See the detailed description, particularly under pyrochroite and willemite, pages 49–50, 86–87.) The Taylor mine, the deeper workings of this area, yielded similar minerals.
9.	The Franklin Iron Company’s quarry is in white limestone cut by pegmatite veins. Abundant metamorphic minerals, notably graphite, pyrite, pyrrhotite, arsenopyrite, fluorite, edenite, titanite, norbergite, tourmaline, and spinel, have been found there.
10.	Furnace locality. In excavating in limestone for the foundation of the old iron furnace, pockets were found containing corundum, spinel, rutile, marcasite, mica, hornblende, and other minerals, according to Mr. Hancock.
11.	The Furnace quarry is an abandoned quarry in white limestone, which formerly yielded numerous metamorphic minerals similar to those found at locality 9.
12.	Ball’s Hill is the site of numerous magnetite mines, including the Hill mine and the Gooseberry mine, where were found scapolite, zircon, pyroxene, black garnet, and many other minerals.
13.	The Fowler quarry, in white limestone, was once noted for crystals of pyrite and green tourmaline isolated in limestone. More recently pyrrhotite, brown tourmaline, graphite, edenite, spinel, and phlogopite have been the chief minerals found.
14.	At this locality were found loose boulders of limestone containing, according to Mr. Canfield, large crystals of phlogopite.
15.	At this locality, on the east leg of the ore body at Sterling Hill, was found the pocket containing the largest crystals of franklinite and of troostite in the Canfield collection. The principal locality for roepperite was nearby.
16.	The calamine pit of the Passaic mine yielded most of the finer specimens of calamine and of large red garnets and the minerals chalcophanite and hydrohetaerolite.
17.	The Lord Stirling pits were those from which zincite was mined by Lord Stirling about 1772.
18.	The calamine pit of the Noble mine, in which the calamine was mostly iron-stained, yielded corundum and the only tourmaline found in the zinc deposits.
19.	The dysluite locality was an opening in the wall of the east leg of the ore body at Sterling Hill, where were found the remarkable large gahnites with garnet and jeffersonite, preserved in the Canfield collection.
20.	At the mouth of a tunnel into the Noble mine was found a large pocket in limestone, containing large and complex crystals of aluminous pyroxene and amphibole.


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