Is this black Glass?

by Lauren S
(Los Angeles, CA)

I've read that black glass can appear an olive green or amber color when held up to the light and I'm trying to find out if this qualifies as "black glass". 

Some of the pieces are so thick and dark that light can't penetrate thru them.  Others are greenish.

I found a rather large amount of glass shards on an isolated beach off the coast of Panama.  It's seems fairly old and this has piqued my interest in beach glass, that's for sure!  What a fun hobby!

Thank you for your help!

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See this:

• Central America Sea Glass