Help please!

[murrini]

I'm baffled on this one (though it doesn't take much to baffle me!)

This was found in Northern California, in Southern Trinity County. We are finding lots of Nephrite, Jasper, Chert, Serpentine, Greywacke, a beautiful blue schist, & Shale in the areas where we found this rock, and there are lots of manganese deposits in this region. It is a very dark blue with pink & orange veining through it, there are metallic flakes under the surface that are quite large, sort of coppery colored, When cut it remains dark blue with green flecks in it, there is a vein of very translucent almost clear substance in the piece we cut (but the main blue does not have any translucence. The streak is very dark grey (maybe dark blue, can't tell, streaking on 100 grit sandpaper) it was quite difficult to cut - similar to cutting jasper and made a very dark slurry. A good pocket knife will not scratch it. There is a strong oxidation on one side, and most is nicely water polished but one side is very very rough. Seems very dense, bounces back a sledge hammer like the nephrite does. It is approx 2 ft across, weighs 203 lbs.

Link to it's album:
camasranch.com/Gallery/index.php/Blue-Pink-Thing

(The pics were in full sunlight so changed the color some, I can't correct them quite right. Pics of other samples from this area in the rest of the album if it would help identify this one?)
Thanks!!

[arappaho]

Well Dang, murrini, that's the way to post a question about a rock!

I saw your post this morning and was hoping someone else would
jump in with an opinion, but since there ain't, I didn't want to leave
you hanging you did such a good job with description and pics!

Now you obviously have done some rockhounding out that way and
the only place I've ever been to in California is DisneyLand and the
LA airport, but.........I know you know you have a lot of Basalt out
there.
This definitely looks like an igneous or volcanic "flow" rock to me.
Maybe the blue tint to it is making you think it's something other than
Basalt? Basalt is grey to black, but then again, there's that old
saying, Looks so black it's blue. Greys can do that too.

We don't have much true unmorphed Basalt here in the southeast
so I've been reading about Flow Basalt in my Audubon Fieldguide.
Says the top side of the flow will have the rough scoria type
surface and there are a couple dozen different accessory minerals
that can be in it. Lots of Zeolites.
Just guessing here but the coppery looking metal could be copper.
The little green flecks could be epidote.
The veins of reddish or orange could be Magnetite or even Hematite.
One way to tell if there is a magnetic attraction is to pass a
compass slowly, and steadily, by the vein and see if it makes the
compass jump. In this case it would probably be easier than
passing the rock past the compass.
Could also be that some silica has filled some cracks in that rock?

Anyway, that's what I'm guessing. Let me know what you think.
Good luck slabbing that sucker and thanks for the post.

Also, I don't know if you are familiar with Ben Halpin out there in
Chico, but he's a good old rockhound and can answer alot of your
questions if you're ever in that area. HalpinsRocks.com.

Joe

[murrini]

Thank you very much for your thoughts! Sorry for the delay in replying, I ended up on an unexpected road trip helping a friend move and after 8 hours of driving each day have been exhausted!

Basically I am very very very green to all this rockhounding and can only say with confidence what we have been finding because of wonderful people helping us out to ID our finds! I'm learning, slowly but surely... We are in such a remote and rural area here finding what is 'susposed' to be here through research is very difficult, it seems very few comprehensive geological studies have been done, or if they have I can't find them or correlate them to other studies. I hadn't heard much about basalt in our area up here but a quick google search for our county at least shows that our county should have quite a bit, though most discussions about our county discuss a very different geological area north of us, we are a hidden forgotten part of the county/ world here so I will do more research there as right off I'm not seeing much for our area. Our area is also not susposed to be 'volcanic' according to most reports I can find on the area, though there is a very suspicious 'cone' looking peak that the locals (esp the Indian descendants from the area) seem to associate with volcanic activity (Black Lassic), actually a quick google on it puts it made of Basalt & other volcanic rocks, OR mudstone/Sandstone depending on the site, and contrasting reports of inactive volcano vs. not volcanic at all... I do know a lot of serpentine is in the area of the Lassics & we are finding most of it to attract a strong magnet so will definitely check this one when we get home. This was found just a few miles as the crow flies from the Lassics (>5 maybe?)

We were thinking copper too on the flaking, they mined quite a bit of copper to the south of us, and there isn't supposed to be gold on this end of the county.

I think, because I am so green and will not trust myself on IDing these rocks for a long time, and this one is definitely WAY above and beyond me, I will take it to our local gem & mineral shop, who are wonderful, just far away... I'll be sure to post their thoughts on it, though it may be a week or more before we get there. I Thank You again very very much for your help! I'll definitely look close at it again when I get home with your suggestions and have already learned a ton from you just finding areas to research based off of your suggestions!