Types of Rocks on Long Island: Common Collectible Rocks and Fossils You Can Find

 Before the last Ice Age, Long Island was a valley.

When the glacier came along, though, it gouged out Long Island Sound.

As it retreated, it left on Long Island rocks it had pushed in front of it.

Types Of Rocks On Long Island 

1. Quartz 

Quartz is the most common of minerals and is found in all three types of rock: igneous, sedimentary, and metamorphic.

When the rock is eroded or worn away, the quartz stones are left on beaches, river beds, and soil.

Quartz crystals are hexagonal in shape and come in several colors such as yellow, orange, black, white, and purple.

This type of stone is different from the quartz that is mined.

That stone is full of impurities and flaws.

It’s blended with other types of stone to make countertops for homes.

It does, however, have electrical properties, making it ideal for use in electronics manufacturing.

All kinds of quartz stones are found on the north shore of Long Island.

They look like any other rock with brown, sandy-colored, or gray colors.

These rocks sparkle, though.

To collect them, look for the sparkle.

When you crack it open, you’ll see the quartz crystals. 

2. Rose Quartz 

Abundant and the most common of quartz stones, rose quartz is called so due to its rich pink color.

This famous color comes from an aluminum borate silicate substance called dumortierite.

The mineral ranges from deep dark blue to green, purple, and light pink, to name a few. 

Rose quartz is mainly used for jewelry, with cabochons being the most commonly used in bracelets, necklaces, and earrings.

Rose quartz beads of different sizes and grades of pink are normally used in jewelry making.

You’ll see rose quartz carvings in museums. 

On the north shore of Long Island, you’ll find pinkish rocks.

Look closely, because you could be holding rose quartz instead of a rock.

They’ll have white streaks and sometimes orange streaks from the iron oxide in the rock.

3. Red Shale 

Red shale is one of the types of rocks on Long Island.

Basically made of mud, shale can be broken down into clay.

Mixed with water and other substances, clay is used to make building bricks, bricks for roads and driveways, roofing tiles, cement, and terra cotta planting pots. 

Also found on the north shore of Long Island, red shale is alternatively known as iron oxide concretion, which is a sedimentary type of rock.

These rocks look like the clay pinch pots our kids made for us in kindergarten.

They’re called Indian “paint pots.”

The paint part of it comes from the iron oxide in the shale.

When it’s wet, it produces a reddish substance the Indians used as war paint. 

Collecting shale rocks is a simple matter of finding stones flat as a penny and much the same color.

To find Indian “paint pots,” search for the red stones with small indentations.  

The north shore of Long Island is almost the last place left in which to find these stones.

4. Conglomerate Rock 

A conglomerate is a combination of something into one large entity.

From a kid’s point of view, if you took jelly beans and poured honey or pancake syrup over them and allowed them to harden, you’d have a conglomerate rock.

In the case of Long Island sedimentary rocks, the pancake syrup is a kind of cement made up of quartz and calcite.

The stones in the conglomerate are generally washed down from upstream.

All types of rock, such as sedimentary, igneous, and metamorphic, are included in conglomerate.

Sandstone, granite, gneiss, basalt, limestone, and quartzite are the most common.

They’re bound together with a combination of sand, mud, and calcite or quartz.

If you’re walking the north shore of Long Island looking for these rocks, then seek out something rough and grainy.

The pebbles in the conglomerate can either be the size of jelly beans, or they can be quite tiny.

The stone itself can be red, gray, white, blonde, or black.

5. Gneiss  

Gneiss is a metamorphic rock created at high temperatures and high pressure deep inside the earth.

Found on the north shore of Long Island, this rock is usually black with stripes of white.

It’s that way because, during the heat and pressure, mineral grains got in the way.

They were re-formed into bands across the rock. 

Gneiss isn’t defined by its composition, rather it’s more commonly defined by its bands.

Some minerals are more clearly represented, such as garnet and granite.

Although gneiss is mostly used in road construction, it can be cut and polished for use in tile flooring and countertops.  

While you’re walking the beaches on the north shore of Long Island, look for stones closely resembling granite.

The grains of feldspar identify a stone like granite, and it will be the same with gneiss. 

6. Schist 

Long Island might not have been the site of metamorphic activity, but there was once one nearby.

That’s the only way ordinary sedimentary and igneous rocks could be mixed with metamorphic heat and pressure to produce yet another product.

In this case, flakes of minerals in the shape of plates have been combined with sedimentary rocks which then metamorphosed into the other product.

As in the above case, schist doesn’t require a specific mineral composite to be called schist.

All it needs is enough minerals formed into plates that can be sheared off or foliated.

Some of those minerals are mica, feldspar, quartz, biotite, and garnet.

There are even precious gems such as rubies and emeralds caught in schist stones.

While collecting specimens on the north shore of Long Island, seek out black or brownish rocks with sparkling plate-shaped minerals.

The mineral plates will be aligned in such a way that if you sheared off the crystals, the resulting stone will be just as solid as the rock from which it came.

7. Amphibolite 

Another of the types of rocks on Long Island looks like black granite.

It is, in fact, a mineral that is then formed in the heat and pressure deep in the earth into both metamorphic as well as igneous rocks.

You might pick up such a stone on the north shore beaches, but be aware that the minerals occur in a variety of colors, such as green, violet, yellow, and blue.

Amphibolite’s hardness makes it suitable for use in architectural designs.

The outside of buildings, the flooring inside, as well as wall panels, are often built using amphibolite.

The mineral is also cut into slabs for countertops.

It looks so much like black granite that they’re often sold as such.

Final Thoughts 

People collect stones for their beauty, their history, or their shape, color, and texture.

It’s also fun to find out facts about rocks found on Long Island beaches that no one else knows, so enjoy!