Image: Wikimedia Commons

opal

Silica mineraloid

Instance of: mineral species
1
Sources
1.Stated in The IMA List of Minerals (November 2018)
View statement on Wikidata ↗
Subclass of: solid geologic material

Overview

From Wikipedia, the free encyclopedia · Read full article · Text CC BY-SA 4.0

Opal is a hydrated amorphous form of silica (SiO2·nH2O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to the amorphous (chemical) physical structure, it is classified as a mineraloid, unlike crystalline forms of silica, which are considered minerals. It is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, marl, and basalt.

Overview

All data

47 statements · 30% with external sources · numbers in brackets are citations

Formula: SiO₂·nH₂O
1
Sources
1.hedendaagsesieraden.nl/2023/04/10/opaal/
View statement on Wikidata ↗
Nickel-Strunz 9th edition (updated 2009): 4.DA.10
1
Sources
1.Stated in IMA/CNMNC List of Mineral Names (March 2009)
View statement on Wikidata ↗
Nickel-Strunz '10th ed', review of (9th ed/ 2009 update): 4.DA.10
1
Sources
1.Stated in MinDat
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IMA status and/or rank: grandfathered mineral (G)
1
Sources
1.Stated in The IMA List of Minerals (February 2013)
View statement on Wikidata ↗
Streak color: white
Different from: Opal criterion used: descriptive page and disambiguation page have to be in different items · applies to name of subject: Opal
Opale criterion used: descriptive page and disambiguation page have to be in different items · applies to name of subject: opale
IMA Mineral Symbol: Opl
1
Sources
1.Stated in IMA–CNMNC approved mineral symbols
View statement on Wikidata ↗
Strunz 8th edition (series ID, updated): IV/D.01c
1
Sources
1.Stated in Mineralogische Tabellen : Eine Klassifizierung der Mineralien auf kristallchemischer Grundlage, mit einer Einfuhrung in die Kristallchemie (1982)
View statement on Wikidata ↗

On other databases

34 identifiers linking opal across the web's reference databases

Data quality

statements

30%

externally sourced

Source last edited September 1, 2026. AIDB refreshes this page daily.

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AIDB. (2026). opal (Q171058). Retrieved from https://aidb.si/e/opal-Q171058