Crimson Obsidian Identification Guide
Identify Crimson Obsidian as a red-toned volcanic glass by its conchoidal fracture, glassy luster, and warm hematite coloring versus look-alikes.
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What Crimson Obsidian Looks Like
Crimson Obsidian is a volcanic glass colored deep red to reddish-brown by finely dispersed iron oxide (hematite/magnetite) inclusions. The red often blends with black, producing mahogany streaks, blotches, or a smoky crimson glow when backlit. Like all obsidian it is amorphous (non-crystalline) with a bright, glassy surface.
- Luster: vitreous (glassy), high shine
- Transparency: translucent crimson on thin edges, opaque in mass
- Habit: massive glass with no crystal structure; smooth curved (conchoidal) surfaces and razor edges when broken
- Color: crimson to brick red, often mixed with black
Step-by-Step Field-ID Checklist
- Look for glassy shine and curved fracture. Obsidian breaks in smooth, shell-shaped conchoidal scoops with sharp edges.
- Backlight it. Thin edges or chips glow red, confirming glass colored by iron oxide rather than a solid red rock.
- Check for gas bubbles or flow lines. Tiny stretched bubbles and swirls are common in volcanic glass.
- Test hardness. It scratches glass-marginally (Mohs ~5-5.5) and feels hard but is more brittle than quartz.
- Rule out crystals. True obsidian has no visible mineral grains; if you see crystals it is not obsidian.
Key Diagnostic Tests
- Mohs hardness: ~5-5.5 (softer than quartz; a steel file bites slightly).
- Streak: white to pale gray.
- Fracture: conchoidal, extremely sharp edges.
- Magnetism: may show faint attraction to a strong magnet from iron-oxide content.
- Density: ~2.35-2.6 g/cm3, noticeably lighter in hand than dense red minerals.
Common Look-Alikes and How to Tell Them Apart
- Mahogany obsidian: Essentially the same family; mahogany obsidian leans brown with black, crimson leans pure red. Distinction is color, not composition.
- Red glass (man-made slag/cullet): Manufactured glass can look identical. Look for natural flow lines and bubbles; perfectly clean, evenly colored glass with mold seams is artificial.
- Carnelian/red chalcedony: Harder (Mohs 7), waxy not glassy, and lacks gas bubbles and flow banding.
- Red jasper: Opaque, dull-to-waxy luster, no conchoidal glassy shine, Mohs 7.
- Goldstone: Man-made glass with sparkly copper flecks, never natural crimson swirls.
Where It Is Found
Obsidian forms where silica-rich (rhyolitic) lava cools too fast to crystallize, around young volcanic centers. Red-toned varieties occur in the western United States (Oregon, California, Arizona, Nevada), Mexico, and other volcanic regions.
Frequently asked questions
How can you tell if it's real Crimson Obsidian?
Genuine crimson obsidian is volcanic glass: it has a vitreous luster, breaks with smooth conchoidal fractures and razor edges, glows red when backlit, and may show flow lines or tiny bubbles. Mohs hardness is about 5-5.5, softer than quartz.
What does Crimson Obsidian look like?
It is a glassy, deep red to reddish-brown volcanic glass, often mixed with black mahogany streaks, that glows crimson when light passes through thin edges.
Crimson Obsidian vs mahogany obsidian: what's the difference?
Both are iron-stained volcanic glass. Crimson obsidian shows brighter, redder color while mahogany obsidian is browner with black banding. The difference is the shade of iron-oxide coloring, not the mineral itself.
Is Crimson Obsidian natural or man-made?
Natural crimson obsidian exists, but red glass is easily faked. Look for natural flow lines, stretched bubbles, and irregular color; mold seams or perfectly even color suggest manufactured glass.
Is Crimson Obsidian the same as carnelian?
No. Carnelian is red chalcedony (quartz), harder at Mohs 7 with a waxy luster, while crimson obsidian is glass at Mohs 5-5.5 with a bright glassy shine and conchoidal fracture.