Black Sea Glass

Wandering the beach, you may come across nuggets that look like smooth black stones, but which are actually black sea glass. Black glass has a long history and each piece has a unique story, depending where it is found.

Black is one of the oldest glass bottle colors, used by early Romans throughout their empire. Black glass from this time period is often actually a very dark olive green or olive amber, and was usually made by adding iron oxide during the manufacturing process. Thick walls and iron oxide made the glass strong and kept out light that might damage wine, ale, cider, oil, or other liquids during shipment and storage. Early black glass pieces, possibly Spanish, can be found in Seaham, England, today. “The earliest pieces found here are quite crude and full of bubbles, olive green in color,” says Paula Newman of PeblsRock. “There were supply ships for the Spanish Armada, which were chased up the North Sea by the English navy, carrying  bottles of wines and oil. Records show that of these Spanish ships, at least 28 were lost in storms along the East and North East coast.”

Black glass comes in many colors, including blue-black glass gin bottles from Holland and red-black glass bottles from Portugal. Some black glass may have started out as another color, including pink, purple, yellow, and other colors, but are either so thick or have darkened over time so they appear black. Some pieces may have been waste glass from the production of flash glass. “Items were not made with this dense glass that appears black but a thin coating of this glass in its molten state would have given flash glass a vibrant color,” says Jane Milburn of the black sea glass nuggets she finds in Seaham today. 

Other sources of black glass are liquor and ale/beer bottles that were mass produced in the late 19th century around the world. Square black glass bottles—actually dark forest green—were used for liquor, bitters, and medicinals in the mid 19th century. 

Gail and Bruce Barton, sea glass jewelers who spend the winter months in the Abaco Islands in the Northern Bahamas, find pieces of black sea glass from these square bottles. “Case Gin produced square bottles for sea shipment to better utilize the space in shipping crates,” says Gail. “As boaters, Bruce and I think these producers must have been geniuses. Square wine bottles would certainly help alleviate our storage problems on board.”

Wandering the beach, you may come across nuggets that look like smooth black stones, but which are actually black sea glass. Black glass has a long history and each piece has a unique story, depending where it is found.

After the turn of the century, the use of black glass for bottles declined, and lighter olive and amber colors came into use. However, in other regions, new uses for black glass developed. In Conneaut, Ohio, General Electric had a lamp base plant that produced black Vitrite insulators for light bulbs for almost 70 years, from 1941 to 2008. Vitrite is glass made with lead oxide and manganese oxide, which gives it a dark purple color. According to locals, discarded glass from the plant was used as landfill along Lake Erie in the mid-20th century. Visitors to the beach there find plenty of pieces of black sea glass, now tumbled smooth by years in the waves. Many pieces are so opaque and large that no light gets through the glass, but smaller pieces or edges show their beautiful violet color. 

Glassware in a color called “Black Amethyst” has been made since the 1860s. When it is held up to the light, it shows its deep purple color.

Although modern storage and transportation systems make the need for light– and breakage-resistant bottles less critical, many liquids still come in lighter versions of the same colors. “Beers are usually in dark amber glass, and wines are still sold in dark green or sometimes red bottles, or occasionally blues from Germany,” notes Paula Newman. 

Finding black sea glass isn’t always easy, as it looks like rocks on the beach. “Black sea glass is often overlooked when beachcombing,” says Gail Barton. “In order to identify any piece of sea glass, you need to hold it up to the sunlight to validate its transparency. Next time you are searching for sea glass, you may find that some of those black stones you observed are actually very old pieces of black sea glass.”

View Caribbean glass from the collection of Wiesy Lauffer

This article appeared in the Beachcombing Magazine March/April 2019 issue.


Watch videos about all the colors of sea and beach glass

Learn more about sea and beach glass colors:

where does sea glass get its color


Simone, check out Paul Chatenay on fb. He makes fab mosaics from things he finds. Aberdabbadoo mosaic is good too.

Clare October 15, 2020

Hi I am finding a lot Black Sea glass slag Orange and black grey and black and also blue and grey Colour

Graeme Walton September 22, 2020

I have old big chunks of black sea glass,
I’d like to shoe it to you.
If you tell my how can i send pictures please.

Zeinab Oss February 12, 2020

Ok so I was walking on the beach on the isle of Palms in SC and came across black coal clunkers from the turn of the century. These were dredged up and deposited after probably over 100 years. They are TRUE Black and I would assume rare. There are several pieces that I have and they are beautiful ranging in size from a softball down to a quarter. Their shapes and unique formations seem to be rare to me…What donyou guys think

GUS DEMETRIADES September 17, 2019

Simone, I wonder if you could use them in some kind of window display? Like hanging them in a window? Anyway, lucky you!

Kirsti Scott February 19, 2019

I find lots of Black Sea glass, mostly are Hugh bottoms of bottles. Any ideas what can be made out of them?

Simone Carrier February 14, 2019

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