The facts
What darwin Glass actually is
Darwin Glass is classified as an impactite natural glass from the Darwin Crater impact, approximately 816,000 years old, with the composition SiO2 approx. 85-90%, with Al2O3 and FeO; contains nickel and chromium anomalies from the impactor and traces of organic biomarkers from the target vegetation. It crystallises in the amorphous system.
Colour comes from fe2+ gives green to dark grey-green; white frothy varieties also occur, which is also what a laboratory looks at when it is asked whether a colour is natural.
Refractive index 1.48-1.51. Specific gravity around 2.27-2.35. Cleavage: none; often filamentous, frothy and contorted rather than smoothly conchoidal. Those three numbers separate it from most of what imitates it.
Where darwin Glass comes from
Darwin Glass is produced at Darwin Crater and the Andrew River area, western Tasmania, Australia - the sole source.
That is the whole list. A single source makes supply fragile and makes any claim of a second origin worth questioning.
How darwin Glass is treated
Untreated. LEGAL: the strewn field lies substantially within the Tasmanian Wilderness World Heritage Area and Franklin-Gordon Wild Rivers National Park, where collecting is prohibited; legitimate material is old stock or from the small area outside the boundary. Scientifically valuable because the target-rock biomarkers survived the melt. Fakes are slag and green glass. Not CITES.
Treatment changes value, sometimes by a multiple, so it belongs in the description before the price and not after the sale.
What darwin Glass is confused with
In the trade darwin Glass is most often mistaken for, or substituted by, Moldavite, Slag glass, Obsidian or Indochinite.
The separation is rarely a matter of opinion: refractive index 1.48-1.51 and specific gravity 2.27-2.35 settle most of it in a minute, and magnification settles the rest.
What darwin Glass is used for
Demand for darwin Glass comes from mineral collecting, jewellery and decorative objects, which is why one price per carat never covers it.
We quote each application in the unit that trade actually buys in, by the specimen, by the carat or by the piece.
Durability and care
Darwin Glass is 5.5-6 on the Mohs scale, with none; often filamentous, frothy and contorted rather than smoothly conchoidal cleavage.
With no cleavage plane to worry about, the practical limit is abrasion rather than breakage, and it takes daily wear well.
Warm water, mild soap and a soft brush. Avoid ultrasonic cleaners on anything fracture-filled, stabilised, dyed or visibly included.
What darwin Glass costs
As a guide, darwin Glass trades around $2-20 per gram depending on form and clarity; documented old-stock specimens higher.
That is a range, not a quote. Colour, size, clarity, cut and origin move the figure a long way inside it, and the only honest price is one given against a specific stone. Send us what you need and we will price it.
Questions
Is darwin Glass treated, and how?
Untreated. LEGAL: the strewn field lies substantially within the Tasmanian Wilderness World Heritage Area and Franklin-Gordon Wild Rivers National Park, where collecting is prohibited; legitimate material is old stock or from the small area outside the boundary. Scientifically valuable because the target-rock biomarkers survived the melt. Fakes are slag and green glass. Not CITES.
Where does darwin Glass come from?
Darwin Crater and the Andrew River area, western Tasmania, Australia - the sole source. That is the only commercial source.
Is darwin Glass hard enough to wear every day?
Yes. At 5.5-6 on the Mohs scale with no cleavage plane, it handles daily wear well. The practical limit is gradual abrasion rather than chipping.
How much does darwin Glass cost?
Indicatively $2-20 per gram depending on form and clarity; documented old-stock specimens higher. Colour, size, clarity and origin move the price a long way within that, so treat it as a range and ask for a quote against a specific stone.
What is darwin Glass confused with?
Most often Moldavite, Slag glass, Obsidian and Indochinite. A refractive index of 1.48-1.51 and a specific gravity near 2.27-2.35 separate it quickly.
What is darwin Glass used for besides jewellery?
mineral collecting and decorative objects. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for darwin glass?
Tell us the size, the quality and what it is for. We source it, photograph it and quote it — with the locality named.
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