Penn Minerals! - Classic Minerals and More from Pennsylvania

Jay L. Lininger,  Dillsburg, PA


Part four of the chronicle series recounts a little known, but historically interesting aspect of our Keystone State mineralogy: the development of the lead-zinc mines at Sinking Valley, Blair County. The Sinking Valley story begins more than 200 years ago, and for that reason many of the details have been lost in the mists of time. Events were unrecorded, because they were not deemed important at the time. Over the years, I've attempted to accumulate every scrap of information available, including early newspaper accounts. From these sources has emerged the story which follows. Perhaps it will provide the reader with one more piece of the tapestry which makes up the fascinating mineral history of Central Pennsylvania.


Throughout the history of our nation, wars have brought about the need for vital minerals. Such was the case in the development of the metallic mineral deposits in the Sinking Valley. Every student of American history is aware of the "shot heard 'round the world" at Lexington, Massachusetts in April of 1775. It was the starting. signal for the American Revolutionary War. Many American history students may not be aware, however, that lead, a vital metal in the manufacture of bullets to conduct a war, was a scarce commodity in the colonies. At the onset of hostilities, only a few scarce deposits of lead were known. These deposits were located in New York, western Virginia and Connecticut. A few deposits were known in the Northwest Territory (present Illinois) and the Spanish Territory (present Missouri), but they were far removed from the theater of war. Thus a critical shortage of the metal existed.

Images of patriots toppling New York's equestrian statue of King George III and molding the metal into musket balls, or of Philadelphia's ladies sacrificing their table service to provide lead for the Continental Army, were good propaganda. However, it fell far short of meeting the critical need for lead. Thus, when knowledge of a rich deposit of lead in Pennsylvania's Sinking Valley was made known to the Continental Congress in 1777, great interest was immediately generated. The fledgling government was quick to investigate and take possession of the mineral deposit.

The Sinking Valley of the 1770's was a remote and sparsely populated region on the "western frontier." Sinking Valley was a narrow V-shaped valley surrounded by the heavily wooded slopes of Brush Mountain. No organized authority existed in the region and bands of Indians, hostile to white colonialism roamed freely throughout the region. This animosity existed in spite of the peaceable efforts extended by the Penns toward the diminishing remnants of the tribes. It will be remembered by students of American History that prior to the colonization, the region was contested by the French as well. Strategic alliances between the French and several North American tribes helped inflame the hostility toward the English and their "invading agents."

In April 1778, General Daniel Roberdeau and a small task force set forth from Carlisle, the last populated outpost on the frontier, to take possession of the Sinking Valley lead deposit. With authority from the Continental Congress (now housed in York, because of the British occupation of Philadelphia), his mission was to establish a mining and smelting operation in the Sinking Valley. The Sinking Valley region was now, a part of Bedford County, recently parceled off from the vast Cumberland County tract of the original Penn design. Roberdeau encountered no difficulty in locating the remote mineral deposit because mine shafts and open cut trenches already existed upon his arrival. Historians now believe that French explorers may have worked the deposit sometime about 1750. It has also been noted that after the Indian acquisition of European firearms, they too seemed to have a constant supply of lead for ammunition. The Sinking Valley may well have supplied regional tribes with the vital metal, and even more likely the tribes may have shared that knowledge with the French who rarely explored deeply into Penn's colony. Knowledge of the lead occurrence, had already been shared with the Penn heirs prior to the Revolutionary War. They employed a George Wood of Bedford County to survey the region. In 1776, a parcel of sixteen thousand acres which contained the mineral deposit was set aside and retained by the Penn family, while the surrounding land was sold.

Roberdeau set about to secure the area and set up the much needed operation. In order to attract settlers and provide a secure environment from Indian attack, Roberdeau commenced the construction of a stockade near the mines. The thin soil and hard limestone bedrock in this portion of the Sinking Valley required him to build a structure with horizontal timbers, rather than the familiar vertical arrangement in which the uprights would be buried in a deep support trench. The resulting structure, known as the "Leadmine Fort" (and later, Fort Roberdeau), was unique among Pennsylvania frontier forts because of the design. A crude smelting furnace was constructed inside the stockade. In spite of many obstacles to over-come, the mining and smelting of galena was soon commenced. The associated sphalerite was worthless to the early miners, because the technology required to separate zinc metal from its sulfide component had not yet been developed.

Because of the dire need for the metal, the lead ore was smelted as, fast as it could be mined. Large oak logs were rolled into the furnace traversely, resting on the side ledges. These raised logs from the hearth provided for a draught from the opening at the front of the furnace. Small split logs were set up vertically around the inside of the furnace. Then the ore in chunks of about 15 pounds each were piled in the furnace. The entire top of the pile was covered with logs and the fire started.

After about 12 hours of intense heat, lead trickled from the opening in the front of the furnace. This was collected in a horse-shoe shaped depression dug into the sand-clay mixture in front of the furnace. These horse-shoe shaped "pigs" were then hung over the backs of pack animals and transported to the nearby settlement of Water Street, located on the Juniata River The metal was then transported by flatboat down to the Susquehanna and onward to other forges for further refinement and ammunition manufacture. It is interesting to note that the cost of lead production at Sinking Valley was expensive. Calculating all aspects of the operation, it translated into $600 per pound -- a vast sum for the times.

Once the small enclave was established and functioning, General Roberdeau departed the scene and placed Captain Robert Cluggage in command. Roberdeau, a wealthy Philadelphia merchant, army officer and member of the Continental Congress was anxious to return to his prior duties. A heavy dose of fever had taken him off the front line of combat, but establishment of the lead operation during his period of recovery provided him with another method of serving the war effort.

The lead mining effort at Sinking Valley was short-lived. As the operation finally got into smooth production, the war ended with the surrender of the British forces at Yorktowne, Virginia. The total production of lead metal was recorded as 1500 pounds; a small amount, but most important when it was needed. The cessation of the war rendered further lead production in the Sinking Valley as uneconomical. Another attempt to recover lead for local needs was recorded in 1795, but was of short duration.


Renewed interest in the mineral deposit was developed in 1820. Two operations were begun under the direction of a Scottish miner by the name of Sinclair. The mines, known respectively as the Upper Lead Mine and the Lower lead Mine, were owned by two Pennsylvania entrepreneurs named Musser and Wells. Three shafts sunk at the Upper Mine were reported to be 100 yards deep with six foot tunnels. Much ore was removed but never processed. Perhaps the rapidly expanding, rich mid-West deposits made the new venture unprofitable. The Tri-State district experienced rapid development. during the first several decades of the 1800's.

In the mid-nineteenth century, the country was experiencing remarkable progress in the period described as the American Industrial Revolution. Transportation improved and metal prices climbed. Once again the hopes for commercial mining in the Sinking Valley were revived. In 1852, a new company, aptly named the Sinking Valley Lead Mining Company, was established. Stock was traded on the New York Stock Exchange and a large smelter and other improvements were envisioned. After the initial flurry of excitement, the mining superintendent disappeared, and shortly thereafter, the miners walked. Recorded history gives no explanation for this series of events. A stock scam was. probable, and yet the preparations made by the fledgling company revealed that much rich ore yet remained. The closing of the Sinking Valley Lead Mining Company ended any further hope of a lead industry in Central Pennsylvania.

The turn of the decade was ushered in by the winds of war. With the American Civil War on the horizon, the U.S. mining industry would once again be called upon to supply vast amounts of natural resources. Numbered among them was an increasing need for zinc to be incorporated into the manufacture of brass. The technology to produce zinc spelter from sphalerite had been perfected in the vast zinc district of the Saucon Valley in Lehigh County, Pennsylvania. Now, the previously unusable sphalerite had a value, and large amounts of it existed in certain areas of the Sinking Valley.

In 1864, the Keystone Zinc Company, supported by abundant capital, set up operations in the Sinking Valley. A-large shaft and a reducing plant were established in the north end of the valley near the village of Birmingham. Some prospecting was done in the southern portion of the valley, and an 80 foot shaft was sunk near the original mining location. Three hundred tons of sphalerite was shipped to the smelter from this shaft. The activity of the Keystone Zinc Company encouraged others to prospect the region as well. Many local farmers discovered other veins of lead and zinc ore. The post war period had its upturns and downturns, and although the Keystone operation had several good years, it could not ultimately survive, and ceased operations in 1870.

In 1881, a geological report of Blair County was published by the 2nd Geological Survey. Geologist Franklin Platt was able to visit the Keystone Mine and observe its good condition. His observations represented the first authoritative description of the Blair County metallic deposits. Sporadic prospecting continued over decades and into the twentieth century. The persistent feeling remained that down deep in the brecciated zones of the crushed limestone bed, such as observed in the Keystone Mine, could still produce a bonanza in valuable ore. In 1920 an Ohio company sank a 40 foot shaft and chum-drilled a 213 foot hole on the Albright farm. The shaft was barren, but the drill hole encountered rich ore. No further activity was precipitated as a result of the drilling, but the Albright. farm, located in the vicinity of the original discovery, would be investigated numerous times.


The advent of World War II brought about an unprecedented need for vital minerals. The National Bureau of Mines was charged with the mission to re-evaluate the resource potential of hundreds of earlier mining districts. The Sinking Valley occurrence was among them. Under the direction of McHenry Mosier and Donald Reed, the Albright Farm was once again scrutinized. In 1944, significant surface trenching was undertaken and resulted in the discovery of two previously unknown veins of lead-zinc ore. Subsequent drilling of three sites in 1947, however, produced no new occurrences.

In the 1970's, a renewed interest in the region was stimulated when the 4th Geological Survey undertook to evaluate all known lead-zinc occurrences in Pennsylvania. This effort was a greatly expanded version of an earlier report prepared by Benjamin L. Miller, noted economic geologist of Lehigh University (1924). Directing the lead-zinc study project for the survey was economic geologist and geochemist Robert C. Smith II. The results of this remarkable and comprehensive effort was published in the Report M72 ("Lead-Zinc Minerals of Pennsylvania"). Smith concluded his study of the Sinking Valley area by citing six reasons for further exploration using modem geological technology. In his opinion, past exploration appears to have been solely aimed at near-surface vein deposits. He has suggested that numerous physical aspects of the occurrence point to great reserves at depth. Perhaps the Sinking Valley story has another chapter.

For the mineralogist, the Sinking Valley suite of species is simple and straightforward. Lead minerals were represented by primary galena in shiny cleavages and occasional cubic crystals. Secondary lead mineralization is present in tiny black (often overlooked) crystallized anglesite and small white to clear cerussite. Zinc mineralization was represented by sphalerite in crystalline brown masses, smithsonite in the brown "dry bone"' form, hydrozincite in white coatings and hemimorphite in clear microcrystals. A rare mineral discovered by Smith in tiny metallic blebs in the Keystone Mine, proved to be Jordanite. The rare zinc sulphosalt has not been found in any other Pennsylvania location to date. Gangue minerals include abundant white barite, pyrite, calcite, dolomite and rarely, fluorite. This writer has observed Sinking Valley ore specimens in numerous old nineteenth century collections. The location, however obscure, was known to earlier mineralogists. I was fortunate to obtain some years ago, a well crystallized barite from the Sinking Valley, exant the Peter Zodac collection. I believe Zodac obtained this specimen from a nineteenth century collection.

Can Sinking Valley specimens be collected today? The Keystone Mine is dangerous and inaccessible, but Blair County collectors Pen Ambler and Ed Carper have consistently collected good specimens in the other mine areas and in open fields. I have been fortunate to accompany them on several field trips and collected worthwhile specimens. Most interesting to this writer are the secondary ore minerals such as smithsonite, cerussite and hemimorphite.

A trip to the Sinking Valley area is rewarding. The region is picturesque, and a reconstruction of Fort Roberdeau provides the visitor with Colonial Period imagery. A side trip to the Roaring Spring quarry can always put the icing on the cake.

 Part Five - The Phosphate Minerals of East Waterford, Juniata County