Judging quality
The picture is everything: finely branched, well-spaced dendrites in clean cream material. Crowded muddy patterning is common.
Mineraloid
Dendritic Opal
Common opal without play-of-color, patterned instead by black manganese dendrites branching through pale cream host — sometimes called Merlinite in the trade.
Care
Can dry and craze. Keep away from heat.
History & lore
Dendrites are not plants but mineral crystallisation along fracture surfaces, a classic example of fractal growth.
Cultural history, recorded as tradition rather than as medical or scientific claim.
Common questions about Dendritic Opal
- What is Dendritic Opal?
- Common opal without play-of-color, patterned instead by black manganese dendrites branching through pale cream host — sometimes called Merlinite in the trade.
- How hard is Dendritic Opal and what is it made of?
- Dendritic Opal is a Mineraloid-family mineral with the composition SiO2·nH2O. It crystallizes in the amorphous system and rates 5.5-6.5 on the Mohs hardness scale. It occurs in cream, black.
- Where does Dendritic Opal come from?
- Notable localities for Dendritic Opal include Madagascar, Peru, Turkey.
- How do you tell good Dendritic Opal from filler?
- The picture is everything: finely branched, well-spaced dendrites in clean cream material. Crowded muddy patterning is common.
- How do you care for Dendritic Opal?
- Can dry and craze. Keep away from heat.
See it in person
Photographs only go so far
Both rooms are open six days a week, and there is always someone happy to pull pieces out of the case so you can compare them under the light.