Here is a natural specimen of Darwin Glass from Australia. It's a neat piece! 

Name: Darwin Glass

Locality: Tasmania

Mass: 11.3 grams

Will combine shipping!

Returns accepted within 7 days of arrival for refund of purchase price but not refunded shipping. Returns have to be sent also via priority mail with delivery confirmation and insurance.

International buyers: I will ship to most countries, via priority mail. Italy and India, please contact me before purchasing.