The Oldest and Most Spectacular Mica, Feldspar,
Beryl, and Uranium Mine in the USA.
Open Weekends from
May 15 through June 6, 2010
June 12 through October 17, 2010
Children (4-11) $13
Children under 4 are Free with a paid adult.
July & August 9am-6pm
Last ticket sold 1 hour before closing
The mountains and valleys of New Hampshire are rich with mineral formations. From the southwest corner of the state near Keene to the northern Canadian border near Littleton there are fascinating deposits of a variety of minerals. One of these deposits is known as the Littleton Formation which was formed during the Devonian era approximately 300,000,000 years ago. The mining of these mineral deposits has been an important part of New Hampshire history from prehistoric eras to the present. The Ruggles Mine, in Grafton N.H., is part of the Littleton Formation and has a rich mining and geological history. It is the oldest and largest mine of its kind in the United States. Minerals such as Mica, Feldspar, Beryl, and Uranium were mined at Ruggles for 175 years.
Minerals and rocks fall into three classes of identification, metamorphic, igneous, and sedimentary. All of these mineral formations are found in New Hampshire. Metamorphic rock is formed under extreme conditions of heat and pressure. Igneous rock is formed when magma or molten rock cools and solidifies. Sedimentary rock is formed when wind or water deposit sediments and the sediments become compacted. Sedimentary and igneous rock can become metamorphic under certain conditions of intense heat and pressure in the crust of the earth. Metamorphic rock can also change into another type of metamorphic rock. Heat and pressure do not change the chemical makeup of parent rocks but they do change the mineral and physical properties of those rocks.
The Littleton Formation is classified as a metamorphic rock formation that was originally sedimentary. New Hampshire was at one time completely covered by the sea. As a result, huge amounts of sediment were deposited. Hadley and Chapman describe what occurred during the prehistoric era in New Hampshire.
How Rocks were Made
In early Devonian time, sand and mud were deposited. Thousands of feet, in alternating layers, accumulated to form the Littleton formation. William Barton explains what happened during the metamorphism. For untold years the sediments slowly accumulated on the ocean bottom. The earlier layers, compressed by continually increasing weight of newer overlying sediments, were changed into the sedimentary rocks called sandstone, siltstone, and shale. Eventually these layers of rock grew to be several miles in thickness. The Great Folding and the Rise of Molten Rock; Sometime near the close of the Devonian period, about 300,000.000 years ago, a period of great crustal unrest set in. Western New Hampshire, which for a hundred million had been dominantly a region of wide spread seas, began to be uplifted, never again to be covered by marine waters. This period was marked by two major phenomena; intense compression of the earth’s crust and the rise of molten rock into the crust.
Great compress ional forces, acting horizontally in a more or less east-west direction, squeezed the rocks and forced them to buckle. Gigantic folds, both upwards and downwards, trending north and south were produced.
The accumulation of buried sedimentary rocks were heated, squeezed into great folds, and shattered. The heat and pressure involved were so great that the mineralogical character of the rocks changed entirely. The new rocks were called metamorphic and were characterized by mica schists. The schishts consisted of mica and quartz, with the shiny mica flakes having formed from the pre-existing dull clay particles Without these enormous upheavals and pressure New Hampshire would not be as mineral rich as it is today.
The Littleton formation is primarily mica schist, and surrounds the Ruggles pegmatite. Although there are many pegmatites throughout the Littleton formation, the Ruggles Mine is unique because of its enormous size. The crystal formations within the Ruggles pegmatite are larger than any other ever discovered here in New Hampshire. It is 1640 feet long and 335 feet wide, and is approximately 250 feet deep.
Pegmatites are very coarse-grained igneous rocks, that is, those in which the grains range in size from 5 millimeters to 3 centimeters. The course grain results from the presence of volatiles during the crystallization, thus permitting large crystals to grow; The Pegmatite is light colored because it consists almost entirely of light colored minerals: Plagioclase and perthite feldspars, quartz and muscovite mica.
Over one hundred and fifty minerals have been identified in the Ruggles Mine. The primary mineral of economic interest was mica. Books of mica as large as five feet in diameter have been discovered. Without human intervention, these mineral deposits would never have enriched N.H
The Discovery of Mica
Mica was first discovered in 1803 in Grafton N.H. by a man named Sam Ruggles. It is believed that his origins were English and that he was probably farming and homesteading when he discovered mica on his property. Sam Ruggles knew the value of the mica he had discovered and set forth the first and one of the largest mining operations of its kind in the United States.
For years it is believed that Sam Ruggles went to great lengths to keep the location of his mine a secret. Ruggles put his family to work extracting books of mica. Then, to prevent his neighbors from learning of his discovery, the mica was packed into wagons along with farm product sand transported by ox-team to Portsmouth, N.H. From there it was shipped to England, where it could be sold without arousing anyone’s suspicion as to its possible origin.
As the demand for mica increased, Ruggles would make special trips to Portsmouth in the dead of night, still hoping to keep the location of his mine a secret. There is speculation as to why Ruggles was so adamant about keeping his mine a secret. One possibility is that land was being claimed and not purchased in the early 1800s and there was an acre limit on how much land could be claimed each year. Ruggles may have been trying to claim enough land to cover the entire mountain top to ensure ownership of all the mica outcroppings. This illustrates the value of these resources to N.H.
In the early nineteenth century mica was in great demand for its use in many household products. Because mica is heat resistant and transparent, it was used for the windows in woodstoves and whale-oil lamps. Mica was also used in ships windows. Basically anything that is now made of glass was made of mica in the early 1800s.
By 1840 it was said that 600 to 700 pounds of mica were mined annually, valued at $1500. By 1869 production had increased tremendously, and in that year it was reported that seventy-five boxes weighing 350 pounds each had been mined, making a total of 26,000 pounds.
The production of mica continued to increase into the late 1800’s. The Ruggles Mine reported shipping 3,600 pounds in January of 1877. By the early to middle part of the twentieth century mica mining began to decline. In 1930 as little as 8,000 pounds of mica was mined annually in the United States.
Despite the decrease in production, the value of mica remained high. Clear sheets of mica were still sold at very high prices, and by the early 1930’s an estimated $12,000,000 worth of mica had been mined at the Ruggles Mine.
Later on mica was used as an electrical insulator. It does not conduct heat or electricity due to its molecular structure. Early electrical appliances, such as toasters had mica in them. Mica is still being used today in products from building materials to cosmetics. Mica is in cement blocks and asphalt roof shingles. It is also used in lipsticks and fingernail polish. Most anything that sparkles contains mica.
The Development of Ruggles Mine
The ownership of the Ruggles Mine has changed several times over the years. It is not certain who owned the mine after the death of Sam Ruggles and for much of the rest of the nineteenth century. In 1874, a man named J.W. Kelton is said to have owned and operated the mine. By this time the mica was no longer being hauled away in secret by ox-cart, but being transported out of Grafton by the railroad.
Feldspar was the second most predominant mineral to be of economic interest at Ruggles Mine. The American Minerals company began mining feldspar in 1912. Feldspar was used in the making of high grade ceramics. The Syracuse China company used feldspar in the glazes on their fine china for many years. It was also used in the enamel surfaces of early appliances such as stoves and refrigerators. Feldspar was also in the making of false teeth.
The Bon Ami Company owned and operated the Ruggles Mine between 1932 and 1959. They mined the feldspar for use their non-abrasive scouring powder and glass cleaner. The Bon Ami Company extracted approximately ten thousand tons of feldspar a year during their period of operation.
Beryl is another mineral that was mined at Ruggles Mine. Beryl is the principal ore of the metal known as beryllium. Beryllium is lighter than aluminum and stronger than steel. Today, beryllium alloys are used in atomic reactors, electrical components, and as metal on spaceships components used at NASA. At one time during the mining of Beryl, a mass of the mineral was discovered that filled three freight train cars.
During the twentieth century The Ruggles Mine was reworked several times for the scrap mica that was left behind during earlier operations. The large “books” of mica were no longer being mined, but the smaller amounts that were dumped into waste piles during earlier operations. As new uses for mica were discovered, the demand for it increased once again. It was no longer used for whale-oil lamps, as in days of Sam Ruggles, but now in wallpaper (for sheen effect), paints, roofing, molded insulation, lubricants, etc. All the better grades were used for electrical insulation. The reworking of the mine was done by the English Mica Company of New York. They set up an extensive operation that crushed, screened, and washed the rock to separate it from the mica. The recovered mica was then washed down 3,200-foot flume to a mill at the bottom of the hill.
The Mine remained active and productive for 160 years. In the early 1960’s the U.S. government discontinued subsidizing the mica industry though it’s Mica Stock Piling Program. The result was that domestic mica mining operations could no longer compete in price with the mica imported from Brazil and India. Mining operations were thus discontinued at the Ruggles Mine.
The end of mining mica and other minerals ended an important chapter in the history New Hampshire. Mining provided employment and revenue to many people during the early days of our state. It provided our ancestors with an option to farming as means of survival. The Littleton Formation and the Ruggles pegmatite are what is left of a very significant part of geologic history. The formation was a natural resource that provided income and numerous minerals used in many important products.
In 1963 the Ruggles Mine was opened to the public. For 40 years visitors have been able to come and experience a part of this geologic and mining history. When entering the mine today one can still see where the feldspar and mica of the pegmatite connects to schist of the Littleton formation. One can witness the tremendous forces of the earths folding by observing the layers of schist that stand vertically above the pegmatite. The collecting of minerals is permitted at the Ruggles Mine, one can take home pieces of this history. Exploring the enormous caverns and tunnels provides insight into an event that took place 350,000,000 years ago. A visit to Ruggles provides insight into an important part of mining and geologic history.