Tangerine Obsidian Identification Guide
Spot orange tangerine obsidian by its glassy conchoidal fracture and iron-oxide color, and tell it from carnelian and dyed glass.
Read the full Tangerine Obsidian encyclopedia entry →
What Tangerine Obsidian Looks Like
Tangerine obsidian is volcanic glass (obsidian) colored orange to reddish-orange by finely dispersed iron oxides (hematite/limonite), frequently as a coating or staining on otherwise black or dark obsidian. Much commercial "tangerine obsidian" is natural orange-stained obsidian; some is heat- or surface-treated.
- Color: warm orange, tangerine, to brownish-red, sometimes mottled with black or smoky zones.
- Luster: bright, glassy (vitreous).
- Transparency: translucent on thin edges to opaque.
- Form: massive glass with no crystals; broken pieces show smooth curved surfaces.
Step-by-Step Field ID Checklist
- Look for glass luster. A wet, glassy shine without visible grains or crystals points to obsidian.
- Check the break. Obsidian shows classic conchoidal fracture—smooth, curved, shell-like surfaces with razor edges.
- Hold to light. Thin edges glow translucent orange; internal flow banding or bubbles may show.
- Hardness test. It scratches glass faintly and is scratched by quartz (Mohs ~5-5.5).
- Streak. White to pale; iron staining may give a faint rusty streak on coated surfaces.
- Weight/feel. Noticeably lighter than chalcedony of equal size and warm-feeling like glass.
Key Diagnostic Tests
- Hardness: ~5-5.5—softer than quartz/carnelian (7).
- Streak: white.
- Fracture: conchoidal, no cleavage.
- Density: ~2.35-2.6 (lower than chalcedony's ~2.6 and clearly lower than glass paperweights filled with additives).
- Acid: no reaction.
- Internal features: gas bubbles and flow lines confirm natural glass.
Common Look-Alikes
- Carnelian/orange chalcedony: also orange and translucent, but harder (7), waxier, and shows no gas bubbles; it cannot be scratched by a knife while obsidian can be scratched by quartz.
- Manufactured/dyed glass (slag glass): very uniform color, often with mold seams, perfectly round bubbles, or unnatural brilliance; obsidian's bubbles and flow are irregular.
- Amber/copal: much softer (2-2.5), warm and light, with resinous luster and static behavior—obsidian is far harder and colder.
- Mahogany/red obsidian: related volcanic glass; tangerine is brighter orange while mahogany shows brown-and-black swirls.
Where It Is Found
Natural orange-stained obsidian comes from rhyolitic volcanic regions, with material marketed from the western United States (Oregon, Nevada, Arizona), Mexico, and elsewhere. Because some tangerine obsidian is surface-treated, buy from reputable sources if natural origin matters.
Frequently asked questions
Is tangerine obsidian natural?
Some is naturally iron-stained orange obsidian, but a portion on the market is heat- or surface-treated black obsidian. Genuine natural glass shows irregular gas bubbles and flow banding rather than perfectly uniform color.
How can you tell tangerine obsidian from carnelian?
Carnelian is harder (Mohs 7) and cannot be scratched by a steel knife, while obsidian is softer (about 5-5.5) and shows glassy conchoidal fracture with gas bubbles. Carnelian also has no bubbles.
What does tangerine obsidian look like?
Warm orange to reddish glassy material, translucent on thin edges, often mottled with black or smoky zones, that breaks with smooth shell-like surfaces.
How do you tell tangerine obsidian from glass?
Manufactured glass tends to have very even color, mold seams, and perfectly round bubbles, while obsidian shows irregular bubbles, natural flow lines, and slightly lower density.
Tangerine Obsidian identified by the community
Recent Tangerine Obsidian specimens identified with Rock Identifier.
