Where to look in Basalt?

[OwenT]

Newbie rockhound here, I just read Gems and Minerals of Washington and it mentioned possibility of precious opal being located in the basalt formations of Moses Coulee. I was bored yesterday so I decided me and my friend would just go look around there. After tromping around for an hour or so I concluded that I really have no idea about where to start looking for these opals. Out of all the chunks of broken basalt at the base of the cliffs and stuff I never saw a trace of anything other than plain old basalt. So where would I need to go to look for these things or what clues do I look for? Would they be at the very top of the coulee, in the columns, or in the really bubbly stuff?

 

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[BurntBear]

This is what I found associated with it:

http://www.mindat.org/photo-663650.html

Click the little arrow at the bottom of that page for a description.

 

[OwenT]

Are you thinking that that's the opal that was rumored in the book to have been found in Moses Coulee?

 

[rodoconnor]

Owen, it seems to me most opal is found in close proximity to petrified wood. Find the remnants of an ancient lake bed. Check out fractures and fissures of course . G/L

 

[BurntBear]

From what I read, the Opal has been found associated with the vesicular Basalts located here:

Rock Island Dam, Douglas Co., Washington, USA

 

[OwenT]

Thanks guys.

most opal is found in close proximity to petrified wood

makes sense. We did find two small pieces of petrified wood so I guess we're not to far off from something.

Find the remnants of an ancient lake bed

Look on the surface, or between layers of basalt flows?

 

[Eu_citzen]

The tricky thing is, opal can form in several ways. SO before you guys start confusing each other, get the book "Prospecting For gemstones and minerals" By John Sinkankas.

 

[niffler]

This is how I have found precious opal here in Owyhee county, Idaho. The opal forms in the gas bubble holes in the basalt.

From what I read, the Opal has been found associated with the vesicular Basalts located here:

Rock Island Dam, Douglas Co., Washington, USA