Boulder Opal
gem · uncommon
Quick facts
- Formula
- SiO2·nH2O
- Hardness
- 5.5–6.5
- Luster
- vitreous
- Colors
- various with play-of-color
Boulder opal is a type of opal that forms within ironstone boulders. It is known for its vibrant play-of-color and is often cut with the matrix to enhance durability.
Look for colorful patches within a dark matrix, often with a smooth, polished surface.
Scan yours
Photograph your specimen on arockid.com or in RockSnap / RockID. Three free IDs a day — no card.
Try a live scanComing soon on theApp StoreDownload RockSnap on the App Store — coming soonComing soon onGoogle PlayGet it on Google Play — coming soon
On the App Store, search RockSnap. Links go live when Apple and Google approve the listing. Use the web app today — same account.