Unknown Blue Rock

[NMFishguy]

I found this rock near a stream bed. The area is known for historical volcanic activity. Any ideas? Thanks!

 

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[OwenT]

That's pretty cool, I don't know too much but I'll guess blue obsidian. My reason is that in some of the pictures it appears to have a conchoidal fracture.

 

[stdenis_jd]

Definitely conchoid fractures. Looks like one of three things, or possibly all three lol (I'm an amateur, so take it with a grain of salt )

Blue Jasper
Agate
Chalcedony

The swirl patterns on the right in photo #3 look like 90% of every chalcedony I've ever found. In photo #1 the more "solid" sections look very smooth, almost glassy. Can't completely disagree with obsidian, but I think Jasper is more likely. As far as agate, I guess I just threw that out there LOL

 

[Bajahunter]

Looks like chalcedony but it could be opal.
Do a hardness test.

 

[gunsil]

Definitely conchoid fractures. Looks like one of three things, or possibly all three lol (I'm an amateur, so take it with a grain of salt )

Blue Jasper
Agate
Chalcedony
The swirl patterns on the right in photo #3 look like 90% of every chalcedony I've ever found. In photo #1 the more "solid" sections look very smooth, almost glassy. Can't completely disagree with obsidian, but I think Jasper is more likely. As far as agate, I guess I just threw that out there LOL

Both agate and jasper ARE chalcedony!!

 

[stdenis_jd]

True^^ haha...I guess I was referring to miscellaneous chalcedony of the grab-bag style I'm such a n00b