Stone Explorer Obsidian comparison tool

Compare obsidian, side by side.

Compare seven natural appearances at full size, then follow how volcanic glass forms and later changes.

File 019 · Seven natural appearance records

Two ways in · pick one

Any specimen on the right opens its own file.

How to read the wall

Read how each obsidian variety forms, and how to screen a claim, in the full obsidian guide.

One glass. Different geological readings.

A photograph can describe appearance. It cannot establish origin, treatment, or whether a particular object is natural volcanic glass.

Fixed

Body colour and pattern

Black body colour, Snowflake domains and Mahogany flow textures stay in place while surface glare moves.

Directional

Sheen and iridescence

Gold, Silver and Rainbow effects strengthen, shift or disappear as light, surface and viewer move into alignment.

Later

Change after quenching

Devitrification can develop Snowflake texture. Hydration can form perlite around preserved obsidian remnants.

Sources and image credits

Follow the process, keep the specimen in view.

General sources explain volcanic glass and later alteration. Sample studies explain particular textures or optical effects; their mechanisms do not automatically transfer to every stone with a similar name. For the wider material foundation, read the Obsidian Complete Guide.

USGS · Volcanic glass and rapid coolingFormation · alteration
Use
Silica-rich volcanic melt, rapid chilling, hydration and crystallisation.
Read
Yellowstone’s tool-making lava flows · Volcanic glasses: origins and alteration
Smithsonian · Snowflake Obsidian 45995Catalogued specimen · devitrification
Use
A catalogued example with pale radial cristobalite domains in obsidian.
Limit
The identification belongs to the catalogued specimen; a similar pattern elsewhere remains a visual comparison until tested.
GIA and sample studies · Sheen and iridescenceDirectional optics · sample scope
Use
Directional optical effects and the multiple internal structures documented in named samples.
Read
GIA · Phenomenal gemstone nanotextures
Note
Fire obsidian is a local Glass Buttes optical label; its measured thin-film mechanism is deposit-specific. It is not part of this seven-appearance comparison.
Seven specimen photographsReference appearance · image credits
CC0
Black · Twyla Baker / GeoDIL; Snowflake · Mike Davis / GeoDIL; Apache Tear in Matrix · Pella2.
CC BY 2.0
Mahogany, Gold Sheen, Silver Sheen and Rainbow · James St. John. Cropped and/or resized; no colour alteration.
Limit
Each photograph records one specimen under one set of conditions.