Printable PDF
Have you ever noticed how many stone walls there are in Connecticut? Have you ever wondered who made them? And where they got all of those rocks?
photo: Carol Highsmith, Library of Congress
Early British settlers made many of these stone walls. The settlers came here to farm. But Connecticut was covered with forests. The settlers cut down the trees to make fields and pastures. The soil was full of rocks. They piled the rocks neatly around the edges. The resulting stone walls helped keep the farm animals in a pasture and out of a field.
The cleared soil froze more deeply than the rocky soil during the winter. This led to frost heaves in the spring. The heaves lifted buried rocks toward the surface. Every year, farmers cleared more stones from their fields and added them to the walls.
Stone walls are also important because we can learn by studying the rocks that form the walls. Many of the rocks in these walls have stories!
Where Did the Rocks Come From?
How did these rocks get here? We find clues in the types of rock. Granite is one type of rock found in Connecticut. Granite is a hard, tight rock with small grains. It usually has dark and light flecks. Granite formed 500 million years ago. Pressure and heat deep underground melted the rock and then made it hard again. It later came up to the surface.
Gneiss and schist are the two most common types of rocks in Connecticut. Gneiss has clear dark and light bands. It also formed from pressure and heat. You can tell schist from gneiss because it is less banded and has a wood-like grain. These rocks formed 300 million years ago.
Over millions of years, wind and water changed the geography of Connecticut. Tiny bits of rock that water and wind rub off piled up in the Connecticut River Valley and created layered rocks. Layered rocks are called sedimentary rocks. Brownstone is a soft, reddish-brown type of sedimentary rock. Brownstone was later quarried in Portland to build buildings—including many in New York City!
All of these types of rocks show glaciation. Glaciation is when thick sheets of ice moved from the Arctic across Connecticut. The last ice sheet moved across the state 20,000 years ago. When the ice moved, so did rocks. The ice was heavy. It crushed rock into mud. It ground stone against stone. This created the stripes, or striations, we see today.
When the climate warmed and the ice melted, the water carried rock, sand, and fine soil into the river valleys. About 15,000 years ago, there was no ice left in Connecticut. There was only rocky, lifeless soil.
Tundra formed first. Tundra is a community of tiny flowers and shrubs that grows in cold, windy conditions. The climate continued to warm, and trees began to grow in the tundra.
Christmas tree farm in Connecticut. photo: Carol Highsmith, Library of Congress. Conifers below and deciduous trees (trees that lose their leaves in the winter) behind.
Conifers were the first trees to grow. Examples of conifers are pine and spruce trees—think Christmas trees! Birch, oak, maples, and other kinds of green, leafy trees came next. The roots of the trees were strong. They broke apart the hard glacial soil, and the fallen leaves helped form rich, dark soil.
How Rocks Tells Us When the First Peoples Arrived
Rocks also tell us when Connecticut’s first people arrived. Native American activity goes back 10,190 years. This was when most of the trees were still conifers.
These first people built a camp in northwestern Connecticut. They built a campfire. How do we know? Archaeologists found a cracked campfire stone and a charcoal hearth. They guess that fewer than 20 people lived there, and lived there for about a month. They also think the people left and didn’t return. The people moved on to hunt for food.
Steatite stone bowl. Connecticut State Museum of Natural History
Native Americans developed tools from stones. They used hard rocks to carve soft rock (steatite or soapstone) into bowls. Steatite is a soft type of rock that carves easily. It also conducts heat well and can be used for cooking over a fire. Steatite was quarried in the north-central and northwest part of the state.
Rocks for Industry
Northwest Connecticut had good deposits of iron ore. Iron was made in Connecticut from the ore from 1735 to 1923.
Miners dug the ore out of the earth. The ore was then heated to high temperature in a furnace built of stone. The heat separated impurities from the iron. The result was called pig iron. A blacksmith then forged the pig iron into tools.
Drilling pegmatite, Glastonbury, 1890s. See httpctexplored.org/the-industrial-might-of-connecticut-pegmatite/
Pegmatite was another important mineral. Pegmatite is a granite-like rock made up of feldspar, quartz, mica, and other minerals.
Pegmatite was first mined in Connecticut before 1825 for its feldspar. The first feldspar mill was in South Glastonbury. In 1908 Connecticut was the leading producer of feldspar in the United States.
To collect feldspar, miners drilled holes in the pegmatite. They filled the holes with dynamite and blasted the rock into chunks. Big stone wheels crushed the chunks to a fine powder.
This feldspar powder was shipped to factories. It was used to make porcelain pottery, glass, cleaners, and fertilizer. One important product was poultry grit. The grit was fed to chickens to help them digest their food.
Mica and quartz are also found in pegmatite. You probably have mica in your home. It insulates the heating wires in toasters and hair driers. Quartz is important in glassmaking but has many other uses, too.
Beryl crystals from the Haddam area. J. W. Peoples Museum, Wesleyan University, see http://ctexplored.org/the-industrial-might-of-connecticut-pegmatite/
Beryl is also found in pegmatite. Beryl is used in making copper and other metals. Beryl can also be gem-quality and used in making jewelry.
Tons of the kind of beryl used for industry were mined in Connecticut. When the Feldspar Corporation closed its Connecticut division in 1991, nearly 200 years of pegmatite mining in Connecticut ended.
As you can see, there are many stories in our rocks! Find out more about Connecticut’s rocks at the Connecticut Museum of Mining and Mineral Science in Kent or the Peabody Museum of Natural History in New Haven. You will be amazed at the riches that could well be found beneath your feet.
Connecticut Museum of Mining and Mineral Science
Connecticut State Museum of Natural History
Peabody Museum of Natural History
This article was adapted from “Written in Stone” by Collin Harty, Connecticut Explored, Summer 2006, “The Kent Iron Furnace,” by Karin Peterson, Connecticut Explored, Fall 2006, and “The Industrial Might of Connecticut Pegmatite,” by John A. Pawloski, Connecticut Explored, Summer 2010.
For Teachers: Find links to these stories on the For Teachers tab, Chapter 1
GLOSSARY
Archaeologist a person who studies history through digging in the ground to find things that can tell him or her about what happened there in the past
Conifer evergreen trees and shrubs having usually needle-shaped
Conduct to help something move through something else
Frost heave ground that is raised by the process of freezing and thawing
Glaciation the effects of a large body of ice moving slowly through an area
Impurities parts of a thing that are not as good as the rest
Insulate a covering to prevent heat, electricity, or sound to pass through
Pasture land where animals get fed by eating the plants
FAQs
Where can I rock hunt in CT? ›
Collins Hill, Long Hill Mine, Tolland, Vernon, East Granby Quarry, Bristol Copper Mine, Roebling Mine, and Old Iron Mine are exceptionally great places. Let's explore a couple of these areas and see exactly why they are such great spots for rockhounding or beachcombing.
Which rock type is most commonly found in Connecticut? ›
— Most people mistakenly refer to the rock commonly found in Connecticut's mineral layers as granite, but most of that rock typically is gneiss — granite that has been heated under pressure hundreds of millions of years ago so that the minerals recrystalized into distinctive layers.
What kind of rocks are in Connecticut? ›
Includes Garnet, Quartz, Tourmaline, Prehnite, Barite, Beryl, Muscovite, Biotite, Lepidolite, Kyanite, Microcline, Cleavlandite, Schist, Gneiss, Marble, Arkose, Granite and Basalt.
Is it legal to collect rocks in Connecticut? ›
Collecting Rocks and Minerals on State Land is NOT Allowed.
Collecting rocks, minerals, plants, or animals on State Land is considered vandalism.
Where can I find gems in Connecticut? ›
The best places to rockhound in Connecticut are old mines and quarries, some of which can be hard to gain access to. Outcrops of schist and basalt in the Connecticut River Valley expose pegmatites, garnets, and other minerals. Ocean beaches and stream gravels also make for great rockhounding sites.
Can gold be found in Connecticut? ›
One place that gold can be found near Harford, Connecticut is in the Farmington River to the north. It is a sizable tributary to the Connecticut River, and is also known to contain very fine deposits of placer gold. Another known gold bearing area in Litchfield County is Spruce Brook.
Can you find obsidian in Connecticut? ›
That's because there is no obsidian in CT. I used to live in MA & did a LOT of collecting in CT; there's lots of basalt, but, no obsidian.
Can you find petrified wood in Connecticut? ›
Dubbed Pomperaugoxylon connecticutense, Latin for wood from Pomperaug, Connecticut, the fossilized wood has been found in a swath of land along Horse Fence Hill Road. The area, about 300 yards wide by a half-mile long, is part of an ancient desert that got pushed up as the supercontinent of Pangaea split apart.
Are there any rocks worth money? ›
Jadeite is the most expensive mineral, or rock, in the world at this time. Price per carat for this costly gem is three million dollars a carat! Jadeite's beauty and rarity are what makes this rock so pricey. With stones coming in a variety of colors, each stone is unique, but still very much looks like Jadeite.
How do I know if my rock is worth money? ›
The Hardness Test
The harder a mineral is, the more likely it is to be valuable. If you can scratch the mineral with your fingernail, it has a hardness of 2.5 Mohs, which is very soft. If you can scratch it with a penny, its hardness is 3 Mohs, and if it takes a piece of glass to scratch it, the hardness is 5.5 Mohs.
Can you dig for gold in Connecticut? ›
Yes, there is gold in Connecticut. Not a lot, but enough to tease and tempt. In Litchfield County, the two hot spots for prospecting are Lead Mine Brook, above the Thomaston Dam, and Spruce Brook in East Litchfield. Spruce Brook, in East Litchfield or Campville, was the scene of quite a little gold rush in the 1850s.
Why are there so many rocks in CT? ›
As farmers cleared those New England forests, they found rocks—lots and lots of them. The glaciers that receded at the end of the last Ice Age left behind millions of tons of stone in a range of sizes. New England soils remain notoriously stony today.
Why are there so many rock walls in Connecticut? ›
The area features many notable stone walls in large part because of its proximity to what Thorson calls “the geological and agricultural center of interior New England,” which provided abundant stones of the perfect size and shape to make them.
Can you take rocks from the beach home? ›
Tyson Butzke, a California State Parks ranger, cited the California Code of Regulations, which bans gathering of any items, even shells, from beaches. Removing a rock is even worse. It is considered “tampering with geological features.”
Can you take rocks from outside? ›
The U.S. National Park Service deems it illegal since it violates code § 2.1 for the Preservation of Natural, Cultural, and Archeological Resources and can subject violators to criminal penalties. Despite it being illegal in private parks, you can take rocks from public parks.
Can I collect rocks? ›
Generally speaking, collecting small quantities of small rocks from roadsides and ditches on public property isn't a problem. Collectors should still ask first, but it's likely okay. If the roadway or ditch is on private property, get the owner's verbal, preferably written, permission first to avoid potential problems.
Where can I find garnets in CT? ›
Garnets can be found either through careful rock breaking or searching the surface and drainages for the dark colored stones. The garnets will usually occur as single crystals attached to small cavities in the rhyolite rock, though they may weather out of the rock, and wash downhill.
How much is ruby worth per CT? ›
Based on what is available in our inventory, the vast majority of rubies that weigh around 1 carat are at least $1,000 per carat. This amount easily doubles if the ruby has not been heat-treated and will increase steeply for rubies that show good color, even if they have been heated.
Can I keep gold I find? ›
If you find gold you are free to keep it without telling a sole. You don't have to report it to the government and you don't have to pay taxes on it until you sell it. This public land is generally managed by either the Forest Service or the Bureau of Land Management. Most of it is found in the western United States.
Can you metal detect in Connecticut? ›
According to the Connecticut State Library, there is no law that prohibits or provides any stipulations against metal detecting on state land.
How deep will you find gold? ›
There is no specific depth at which gold can be found. Examples of this are the Welcome Stranger – the largest gold nugget ever found – which was retrieved at only 3cm (1.18in) below the surface. Oppositely, gold mining operations today take place at a depth of around 3km (1.8 miles) under the Earth's surface.
Where can you find amethyst in CT? ›
| ⓘ Bates' Rock Road | Bill Barrett collection |
| ⓘ Heritage Village | Harold Moritz collection |
| ⓘ Sawteeth Acres | michael otto collection |
| Southford ⓘ Curtis Quarry (Southford Quarry; Southford pegmatite; Southbury rose quartz quarry; Bridgeport Woodfinishing Co. Quarry; Hulls Hill) | USGS Prof Paper 255 |
Are beach rocks worth money? ›
...
The Top 10 Valuable Beach Stones in the World Today.
| No. | Beach Stones | Prices (per carat/piece) |
|---|---|---|
| 6. | Serpentinite | $10-$20 per piece |
| 7. | Petrified wood stone | $0.25-$10per pound |
| 8. | Jasper | $2- $5per carat |
| 9. | Calcite | $1-$5 per piece |
Where can you find Aquamarine in Connecticut? ›
- Quarry Hill, Haddam Neck, Haddam, Middlesex Co., Connecticut, USA.
- Quarry Hill, Haddam Neck, Haddam, Middlesex Co., Connecticut, USA.
- Quarry Hill, Haddam Neck, Haddam, Middlesex Co., Connecticut, USA.
- Aquamarine. Walden Gem Quarry, Portland, Middlesex Co., Connecticut, USA.
Is petrified wood worth any money? ›
Petrified wood does have value to both collectors and jewelry makers, and it is priced between $0.25 and $10.00 a pound depending on its quality and size. This means that petrified wood can be a valuable investment as well as an aesthetically pleasing addition to any rockhound's collection.
Is petrified wood illegal? ›
Petrified wood is a fossil, and it is legally protected in the United States. Please remember that people have gone to jail for collecting petrified wood on lands that do not permit removing natural materials or fossils specifically and do not risk it.
Are you allowed to take petrified wood home with you? ›
Petrified wood is a common term used for wood fossilized by silica, where the woody structure is visible. A free-use permit may be issued to amateur collectors and scientists to take limited quantities of petrified wood for personal use. A permit is required for commercial sales2/ of petrified wood.
Where is the best place to find rare rocks? ›
The best places to look for rocks to collect are quarries, road cuts, outcrops, pay-to-dig sites, river banks, creek beds, mine tailings, beaches, and sites with freshly overturned soil. These locations provide easy access to abundant amounts of exposed, high quality, representative rock specimens.
Where can I have a rock analyzed? ›
- Your state geological survey.
- A natural science museum.
- A college or university with a geology department.
- A rockshop.
- Members of a local Gem & Mineral club or Rockhunting club (many hobbyists are experts at identification)
- Vendors at a Gem & Mineral show.
Can you rockhound anywhere? ›
Rockhounding can occur on public land, private land, or paid dig sites: There are a lot of public lands where people can collect specimens as a hobby, but some lands are off-limits. Private land should only be accessed with the owner's explicit permission.
Is there Flint in CT? ›
Flint can be found in the wild spaces of Colorado, Connecticut, Florida, Georgia, Indiana, Iowa, Kentucky, Maryland, Michigan, Mississippi, Missouri, Nebraska, New Jersey, New York, North Dakota, Ohio, Rhode Island, Tennessee, Texas, West Virginia, Wisconsin and Wyoming.
What kind of rocks are worth a lot of money? ›
- Quartz.
- Opal.
- Topaz.
- Peridot.
- Obsidian.
- Garnet.
- Jade.
- Malachite.
How I know a rock is valuable? ›
The harder a mineral is, the more likely it is to be valuable. If you can scratch the mineral with your fingernail, it has a hardness of 2.5 Mohs, which is very soft. If you can scratch it with a penny, its hardness is 3 Mohs, and if it takes a piece of glass to scratch it, the hardness is 5.5 Mohs.
Are there rocks that are worth money? ›
Jadeite is the most expensive mineral, or rock, in the world at this time. Price per carat for this costly gem is three million dollars a carat! Jadeite's beauty and rarity are what makes this rock so pricey. With stones coming in a variety of colors, each stone is unique, but still very much looks like Jadeite.
Are quartz rocks worth anything? ›
Quartz's clarity earns it a raw price of around $0.01/carat and a gem price of $1-$7/carat. Amethyst, or purple quartz, is the most valuable variety (can reach $15/carat), but pink, rose, and smokey quartz is also valuable. Clearer, more vibrant, and unbroken specimens are the most valuable quartz.
Is there a rock identification app? ›
The KamenCheck and the RockCheck apps are available for free on the Google play store and are adapted for use on Android devices (soon also planned for iOS).
Can I pick rocks from a river? ›
The U.S. National Park Service deems it illegal since it violates code § 2.1 for the Preservation of Natural, Cultural, and Archeological Resources and can subject violators to criminal penalties.
Can I find crystals in my backyard? ›
Crystals can pretty much be found anywhere on your lawn. Besides soil, crystals could be mixed in with gravel or within a rocky area.
Can you find obsidian in Connecticut? ›
That's because there is no obsidian in CT. I used to live in MA & did a LOT of collecting in CT; there's lots of basalt, but, no obsidian.
Where can I find raw flint? ›
Walk along the beach, riverbanks or stream while looking for hard, glassy rocks. You are more likely to find flint alongside water bodies than any other areas. Explore quarries – Flint/chert is a sedimentary rock that can be found in areas where sand, limestone, gem, chalk, and other minerals have been mined.
Why are there so many rocks in CT? ›
As farmers cleared those New England forests, they found rocks—lots and lots of them. The glaciers that receded at the end of the last Ice Age left behind millions of tons of stone in a range of sizes. New England soils remain notoriously stony today.