Moss Opal
Dendritic Opal
A variety of Opal
What is Moss Opal?
Moss Opal is a type of common opal (not a precious variety) that is highly popular as a tumbled stone. Its popularity comes from its interesting, tree-like or fern-like inclusions of iron or manganese oxide. These inclusions are usually black but can exhibit bluish or gray shades. Thanks to its hardiness, moss Opal is often used in jewelry.
Optical Properties
- Refractive Index
- 1.37-1.52
- Pleochroism
- None
- Optical Character
- Isotropic
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Moss Opal before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Where to Find Moss Opal
Moss Opal is a variety of Opal. RockHoundR, the free-to-download rockhounding map from the Ruby Glint team, shows where collectors find opal in the US, with land-access notes for BLM land and national forests. Collecting is banned in national parks.
See where to find opalAlways check the local rules and get the landowner's permission before you collect.
Quick Facts
Physical Properties
- Color
- White, Black
- Density
- 1.9 - 2.3 g/cm³
- Streak
- White
Chemical Properties
- Chemical Formula
- SiO2 · nH2O
- Elements
- H, O, Si
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Moss Opal FAQs
How do I identify Moss Opal?
Moss Opal can be identified by its White color. Look for these key characteristics when examining specimens.
What color is Moss Opal?
Moss Opal typically appears in White, Black. Color can vary depending on impurities and formation conditions.
