Pirate glass, any clue what’s inside?

Hi everyone!! I have found in my collection a beautiful piece of pirate glass, it looks black but when held to the light is green. Does anyone know what the blue, iridescent and gold looking flecks are inside it? It looks like a rim and the thickness of that is 3 cm.

 

What is pirate glass, please?

 

Black glass, or “pirate glass,” is glass that looks black, but when held up to the light, its true color is revealed. For the Outer Banks, the pirate glass is usually dark olive green, often with an air bubble stuck inside which indicates that it was made by hand and thus very old.

 

It is a great big beast of a wedge of a bottle/vessel rim I’m baffled though as to what it has inside it to give it the colours that you can see…. Gold flecks, turquoise, purple, blue, green, pink