Blue shale roadside stop

[Kaljaia]

Behind the dumpster in my 'home town' is a patch of dark blue shale in a seep. I stopped by there today to see if anything interesting was around.




One interesting thing was the amount of white mineral residue that had seeped from between the layers. I assume calcium because that's what we tell everyone the white scale left by the water is, but really I have no idea. I wasn't about to taste any either ;)




Part-way down the patch of shale was a vertical vein of white quartz. It's pretty fractured but kind of neat, so I brought a few pieces back. I don't have the saw set up yet (hopefully this weekend) so I don't know if it holds together or not.



Either way an interesting spot, and since it really is *right* beside the road/dumpster, not exactly out of my way ;) I need to go back when I have more time. I remember finding iridescent green and yellow mineral residue/patina one time in there, but my childhood memory may not be correct.

[jakesrocks]

You might want to try splitting some of that shale to see if it contains any fossils. Not all shale will, but you never know until you try.

[lithicbeads]

Is there caliche up the hill in the sub soil?Shale can have unexpected things such as the emeralds in Muzo Columbia and jadeite in places. Your metamorphic geology there , or lack of it , would eliminate tose things but always look carefully. Clumps of calcite can be treated in muriatic acid to see if there are any minerals hidden inside.

[Kaljaia]

I've not found fossils in that spot, but there are fragments around the corner in a shale hill, and lots and lots of fossils within a mile radius. I'll post pictures when I get to some of those spots again. There's calcite everywhere, often mixed with quartz. I have a piece of green quartz from this hill that I found as a kid (it's back in the Washington hoard). It was a hand-sized chunk of solid dark green. Directly across the road and creek is a volcanic neck that upthrust through the shale. I'll get pictures of it soon; kids climbing in the shale there have talked about lavender and green quartz and calcite, (but they also got stuck and had to be rescued; I haven't retraced their steps yet.) This particular hill is spotted with big basalt chunks but they arrived via a botched dynamite operation back in the 80s and are not exactly indicative of this hill's geology. :) I've vinegar'd some rock from here before, mostly just to get the seepwater residue off it, but haven't used it for mineral identification before. I'll look into that, thanks for the tip!

[lithicbeads]

Muriatic acid fumes are nasty and keep it off your skin. Wear goggles when dealing with it as your eyes are very vulnerable . A safe acid for the most part and sold in hardware stores in the mason's supply area.

[southerly]

I've not found fossils in that spot, but there are fragments around the corner in a shale hill, and lots and lots of fossils within a mile radius. I'll post pictures when I get to some of those spots again. There's calcite everywhere, often mixed with quartz. I have a piece of green quartz from this hill that I found as a kid (it's back in the Washington hoard). It was a hand-sized chunk of solid dark green. Directly across the road and creek is a volcanic neck that upthrust through the shale. I'll get pictures of it soon; kids climbing in the shale there have talked about lavender and green quartz and calcite, (but they also got stuck and had to be rescued; I haven't retraced their steps yet.) This particular hill is spotted with big basalt chunks but they arrived via a botched dynamite operation back in the 80s and are not exactly indicative of this hill's geology. :) I've vinegar'd some rock from here before, mostly just to get the seepwater residue off it, but haven't used it for mineral identification before. I'll look into that, thanks for the tip!

Sounds like a great area for a fossick. Love mixed metamorphic/igneous ground.