Basalt flows.

Mindat Article: Precious Opal at Whelan, Washington
https://www.mindat.org/article.php/513/Precious+Opal+At+Whelan%2C+Washington

The most significant opal discovery in Washington. It was mined for only a few years starting in the 1890s. Another rumored precious opal occurrence at Mondovi (Davenport) in nearby Lincoln county was reported to be false and may have been confused with this locality.

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Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

ⓘ Gemstones

ⓘ Mineral specimens

Mineral List

ⓘ Opal

1 valid mineral.

Detailed Mineral List:

ⓘ Opal

Formula: SiO₂ · nH₂O

References:

Cannon, Bart (1975) Minerals of Washington. Cordilleran, Mercer Island, WA.

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
ⓘ	Opal	4.DA.10	SiO₂ · nH₂O

List of minerals for each chemical element

H	Hydrogen
H	ⓘ Opal	SiO₂ · nH₂O
O	Oxygen
O	ⓘ Opal	SiO₂ · nH₂O
Si	Silicon
Si	ⓘ Opal	SiO₂ · nH₂O

Other Regions, Features and Areas containing this locality

North AmericaContinent

North America PlateTectonic Plate

Pend Oreille DomainDomain

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References

Fischer, Arthur Homer (1918), A Summary of Mining and Metalliferous Mineral Resources in the State of Washington, with Bibliography, p.96

Cannon, Bart (1975) Minerals of Washington. Cordilleran, Mercer Island, WA.

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Unnamed opal occurrence, Whelan, Whitman County, Washington, USAiRegional Level TypesUnnamed opal occurrenceOccurrence Whelan- not defined - Whitman CountyCounty WashingtonState USACountry function showexplain() { $("#locexplain").toggle(); if (typeof movemap === "function") movemap(); }

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Commodity List

Mineral List

Detailed Mineral List:

Gallery:

List of minerals arranged by Strunz 10th Edition classification

List of minerals for each chemical element

Other Regions, Features and Areas containing this locality

References

Unnamed opal occurrence, Whelan, Whitman County, Washington, USA i
Regional Level Types
Unnamed opal occurrence Occurrence
Whelan - not defined -
Whitman County County
Washington State
USA Country