SIGNIFICANT MASSACHUSETTS
ROCKS & MINERALS
This guide to Significant Rocks and Minerals of Massachusetts, and the Massachusetts Mineral School Display Case accompanying it, was prepared by the Connecticut Valley Mineral Club, Springfield, Massachusetts, and presented to area public schools and other interested groups as part of the Club’s ongoing commitment to stimulate discovery and exploration of geological science.
BABINGTONITE Official State Mineral
Babingtonite, the State Mineral of Massachusetts, is named after Irish physicist and mineralogist W. Babington.It belongs to a class of minerals called silicates, and appears as small, wedge-shaped black crystals. It is hard (5.5–6 on the Mohs scale), heavy, and exhibits good prismatic cleavage and uneven fracture. Crystals of Babingtonite growing with Prehnite or Calcite can be found lining basalt, gneiss, or granite cavities. Babingtonite is considered a mineral of interest to collectors and mineralogists.
Babingtonite has been found at a number of locations in Massachusetts. The best known location is a basalt quarry in Westfield. The old Cheapside Quarry in Deerfield has produced many beautiful specimens. Small, but lustrous specimens are still being recovered at Shaft 10 (part of the Quabbin Reservoir Aqueduct), in West Warren.
Source: Simon & Schuster's Guide to Rocks and Minerals
RHODONITE Official State Gemstone
Rhodonite, the State Gemstone of Massachusetts, is an attractive mineral that is often carved and mostly cut as cabochon jewelry. Faceted stones are rare and highly prized by collectors. It is named after the Greek word for rose, rhodon. Its rose-pink color is distinctive. It is often confused with Rhodochrosite which is also pink to red in color, but streaked with white minerals such as calcite and is reactive to acids. Rhodonite does not react when tested with acids and usually is associated with black manganese and pyrite.
The old Betts mine in Plainfield, originally worked for manganese, has been the main source of Rhodonite in Massachusetts. This mine is now on private property.
DINOSAUR TRACKS Official State Fossil
The Connecticut River Valley is world famous for its abundance of Dinosaur Footprints. In 1802 a farmer by the name of Pliny Moody was plowing his field and happened to turn over a rock which had tracks embedded in it. At the time he had no idea what it was, but in 1833, Professor Hitchcock of Amherst College claimed an ancient bird made them. Years later, they were discovered to be made by animals described as dinosaurs. The Connecticut River Valley was actually the location of a few large lakes, which were visited by many different dinosaurs (Eubrontes, Grallator and Anchisaurus), walking in mud flats along the edges. Amherst College has a very large collection of Dinosaur Tracks recovered from the western Massachusetts area and many are on display in the college’s state-of-the-art Museum of Natural History.
Article Contributions: Cornell Nash, Nash Dinosaur Tracks
MARGARITE
Margarite is a pink colored mineral that is usually found with corundum in emery deposits. Margarite is calcium, aluminum silicate that very closely resembles muscovite mica, but is harder. Margarite was first discovered in 1864 by Dr. H. S. Lucas in the town of Chester, when a very rich emery deposit was found and a mining operation called the Chester Emery Mines was started. Emery was mined to make abrasive products such as grinding wheels and wet stones and also ground to produce a type of sandpaper called emery cloth. The Chester Emery Mines was the first emery mine in the United States. Mining operations finally ended in 1913 because of less expensive sources of emery found outside the country. Margarite can still be collected there today along with about 40 other minerals. Collectors have been visiting the Chester Emery Mines for many years to dig through the discarded material known as “tailings” or “dumps” in search of these buried mineral treasures.
Sources : A Field Guide to Rocks and Minerals by Pough Western Massachusetts Mineral Localities by Alan R. Plante
CLAY CONCRETIONS
Clay Concretions are flat round discs of clay and silt that formed under water in the Connecticut River. These formations are not as old as some mineral occurrences in the area but are still estimated to be over 10,000 years old. Native Americans who lived along the Connecticut River in Hampshire County called them “puddle stones” and could very well have used them as money or as jewelry for ceremonies. No one is quite sure how these discs get their almost perfect round and layered shape, but some believe that the mud and clay get spun in a circular motion by moving water, building up layers of clay silt that, over thousands of years, have harden them into the discs we find today. The Hadley and Hatfield areas are known for having some of the nicest concretions in the country. The discs can range in size from 1 inch to 4 or 5 inches across and are regularly sought by divers and collectors today.
GALENA
Galena is a dark gray metallic mineral and the principal ore of lead. Robert Lyman made the discovery of a very rich deposit in 1678 in the Village of Loudville, between Easthampton and Southampton in western Massachusetts. Lead was a necessity to the early settlers for use in their firearms both for protection and to acquire food. The ore was very rich in silver, smelting out about 12 ounces of silver per ton of lead. The mine in Loudville remained in operation for many years, adding to the supply of musket balls for the American Revolution, and for decades thereafter. Ethan Allen of Vermont worked the mines from 1765–1770. The mine was known as the Manhan Mines, named after the Manhan River, which runs adjacent to the mines.
GOSHENITE
Goshenite, first discovered at the Barrus Farm locality in Goshen, Massachusetts, is the colorless variety of the Beryl mineral group. It is also known as "white beryl" or "mother of gemstones."
Popular beryl’s like Emeralds (green beryl), Heliodor (yellow beryl), Morganite (pink beryl), and Aquamarine (blue beryl), are a result of trace element impurities in Goshenite. The base elements found in this stone are beryllium, aluminum, and silicon. The stone’s hardness on the Mohs scale is 7.5–8.
OTHER MASSACHUSETTS ROCKS & MINERALS OF INTEREST
PLYMOUTH ROCK - PLYMOUTH MA State Historical Rock
Although the Pilgrims did not actually land on it, the importance of the 10-ton granite Plymouth Rock to the early history of our country led the Massachusetts Legislature to commemorate it in 1983.
Source: Massachusetts Citizen Information Service
ROXBURY PUDDINGSTONE Official State Stone
Puddingstone , the State Stone of Massachusetts, is a conglomerate rock made up of a mixture of different, irregular sized grains and pebbles held together by a finer matrix, usually formed from quartz sand. The sedimentary rock is formed in river channels and may contain various minerals such as Chromite, Corundum, Platinum, Diamonds, Gold, Sapphire, and Zircon. Its name is said to derive from a resemblance to Christmas pudding. There are different types of puddingstone, composed of varying mixture, found at geographical locations throughout the world. Roxbury puddingstone, principally found in and around Boston, can be seen in many buildings in the Boston area.
GRANITE Official State Building Stone
Granite is an igneous rock most commonly consisting of quartz potassic feldspar and Biotite Mica. Its color can vary: light gray, white, pink, yellow, and, in rare cases, green. Granite is very durable and plentiful, making it very popular as a building stone. Other uses today range from polished granite counter tops to roadside curbstones, headstones, and pen holders. It can take a beautiful polish, can be carved, or used in its natural finish. Granite is mined in several locations in Massachusetts, mostly for industrial and construction applications.
CUMMINGTONITE
Cummingtonite, originally found in Cummington, Massachusetts, in 1824, is a magnesium iron silicate hydroxide found in metamorphic rocks. Cummingtonite commonly occurs as aggregates of fibrous crystals, often in radiating clusters. It is transparent to translucent, varies in color from white to green to brown, and may be pale to dark depending primarily on the iron content. Its hardness is 5–6 on the Mohs scale.
CHIASTOLITE
The mineral Chiastolite, an aluminum silicate, is a variety of andalusite. It is noted for distinctive cross-shaped black inclusions of Graphite and is commonly cut as cabochon jewelry. It has been found in Ipswich, Hatfield, Sterling, Westford, and Lancaster.