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Post by rockpickerforever on Feb 10, 2013 20:14:20 GMT -5
Let's try this again. Please restrain yourself from hijacking the thread :nono: this time. Following are photos taken of a slab, given to me by new member barclay. This piece is the brother to the one he posted earlier, looking for an ID. He found it in the Panoche Hills of California. Hopefully, these photos can help with an identity. It is a dark blue-green, with some white veins. If you look closely at the second to last photo, you can see thin darker veins running through it, almost like picasso stone has. An original edge, very smooth and fine grained. I tried the streak test, and it did not leave a streak, only a scratch on the back of the unglazed tile. So definitely a hard rock. I broke off a piece, and weighed it, it was 9.0 grams. Next I measured the volume of it with a graduated cylinder. It was 3.35cc. So the density of it is 2686.5671641791 kilogram/meter^3. A cubic meter of pure water at four degrees Celsius weighs 1,000 kilograms. So that would make the specific gravity of it 2.69 (I'm pretty sure). I tried to scratch it with a piece of quartz, and it maybe left a little scratch. It also made the tip of the quartz crystal crumble. The unknown rock would not scratch the side of the quartz crystal. I'd say it is just marginally softer than the quartz, so maybe a 6.8 or so. Too bad about the void running through the center of it, but I'll be able to make something with it. It should take a great shine! Any thoughts?? Thanks for the help. Jean
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Minnesota Daniel
freely admits to licking rocks
A COUPLE LAKERS
Member since August 2011
Posts: 891
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Post by Minnesota Daniel on Feb 10, 2013 21:19:40 GMT -5
Do you know how difficult or easy it was to saw? Does any of the rock, this slab or anything else, show any concoidal fracturing -- like glass or agate or jasper? What do the broken surfaces look like?
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Post by rockpickerforever on Feb 10, 2013 22:03:45 GMT -5
Thanks for your response, Daniel. I didn't saw it, so I'm not sure how difficult it was to saw. Just guessing from the hardness, I'd say it was difficult. I don't know if it was hand fed or not (I know barclay said he needed a new blade ), but the surface is not uniform, ie., saw marks, not level) and there is some glazing on the slab. No conchoidal fracturing in the piece that I received. The place where I broke the piece off to measure it, it's definitely not conchoidal, just looks like a break. I'll try to get some photos of the break tomorrow and post them. Thanks again for your time. Jean
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Feb 10, 2013 22:42:46 GMT -5
it's jasper or some other form of chalcedony.
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Post by rockpickerforever on Feb 11, 2013 10:09:05 GMT -5
Thanks, Scott. I think it'll be the next piece I cab up. Jean
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barclay
has rocks in the head
Lowly Padawan of rocks
Member since November 2011
Posts: 510
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Post by barclay on Feb 12, 2013 22:01:29 GMT -5
Ok, let me try this again with the photos of the slab and the cab I made from it. I hope I do this right. To answer the questions: This was hard to cut. It felt like I was trying to cut something as hard as an agate. The only thing that saved me was that the stone was only about 6" long and 4" wide at most. I fed it by hand because it was small. My good old 10" Harbor Freight brick saw did the deed. Like a lot of the rocks I picked up in the area (Panoche Hills of the Blue G/Lawsonite discussions) it looks like the blue material was broken up under ground and reformed. I have some killer pieces that are rust brown with white quartz gluing them back together. I wish I found more pieces of this blue material. There has also been talk of blue schist in the area. Thanks for help in figuring this out.
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metalsmith
Cave Dweller
Member since October 2012
Posts: 1,537
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Post by metalsmith on Feb 13, 2013 15:20:22 GMT -5
There is blue-schist rock - and blue-schist facies.
Blue-schist facies is a descriptive term for the amount of heating and pressure. Specifically, the temperatures are relatively low for the high pressure conditions experienced in the deep subduction zone (where the ocean's conveyor runs down against / under the continent).
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Post by rockpickerforever on Feb 19, 2013 12:00:53 GMT -5
Well, better late than never... Here's a few photos of the break, that I promised I'd post. Don't know if they help or not. Not conchoidal, and definitely not fibrousy like jade. It has a "quartzy" feel, if that makes sense? Dry The rest are wet Jean
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