Dendritic Opal is a common opal variety characterized by fern-like or tree-like inclusions of manganese or iron oxides. These distinctive dark brown or black markings often resemble natural landscapes and are typically found within massive white to translucent opal matrix. Collectors prize these for their natural artistic patterns, which are most visible when the material is cut into cabochons.
Is this dendritic opal?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch dendritic opal with a known reference. Dendritic Opal sits at Mohs 5.5-6.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Dendritic Opal leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Dendritic Opal typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, cream, colorless, brown.
- 5Look at form & habitCrystal system: amorphous. Typical habit: massive.
Often confused with
Dendritic Opal vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside dendritic opal
Minerals reported to co-occur with dendritic opal. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SiO₂·nH₂O
- Mohs hardness
- 5.5-6.5
- Density
- 1.9-2.2 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Amorphous
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Decorative, Collector
- Host rock
- Volcanic and Sedimentary Environments
- Typical price
- $5-50 for small polished specimens, $50-200 for large display pieces
Where rockhounds find dendritic opal
Classic worldwide localities
- Australia
- USA
- Mexico
- Turkey
- Madagascar
Field-hunting tip
Look in volcanic and sedimentary environments country — that is the host setting where dendritic opal typically forms. If you start seeing quartz, chalcedony, pyrolusite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find dendritic opal on the map
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