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Post by snowmom on Mar 1, 2015 6:49:37 GMT -5
I have had a crush on this rock for quite a while. Jugglerguy and I have found blue-grey-black rocks with spots and a bit of streaking and thought of its similarities to OJ. This piece is very dense, around 6.5 to 7 MOHs, and resembles those smaller pieces, but also seems to have a great deal of some sort of feldspar breccia in the center. I put photos of it on a facebook group I belong to and one of the members suggested it might be variolite. I looked up variolite, and mindat.com says it should not be in use as a rock description, but searches revealed it is metamorphic pillow basalt with high feldspar content. I am thrilled because this also throws light on all those super dense black rocks I have found with feldspar and other inclusions. Websites I have gone to say variolite is rare, but I suspect it is because they are trying to sell it to me. (lots of rare rocks and gems seem to be highly available on the internet, did you ever notice that?) Just had to post this because it is a huge insight on my quest to figure out some of the material I find here, and great confirmation of the 'super dense basalt' diagnosis for many of the pieces of black rock (wannabe jade) that I sent to many of you. Not giving up the quest for jade, but this will help me sort things out. Comments and insights welcome! thanks for looking.
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Deleted
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Post by Deleted on Mar 1, 2015 10:05:48 GMT -5
Frank (lithicbeads) on another forum finds a lot of variolite on the upper coast of Washington. It VARIES a lot. And it is not rare there because he just posted more yesterday.
Jim
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Deleted
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Post by Deleted on Mar 1, 2015 10:53:48 GMT -5
How did you determine Mohs?
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Post by washingtonrocks on Mar 1, 2015 12:38:34 GMT -5
Frank (lithicbeads) on another forum finds a lot of variolite on the upper coast of Washington. It VARIES a lot. And it is not rare there because he just posted more yesterday. Jim I've got a pretty decent hoard of Variolites from local beaches. Never really done much with them except admire their "warty" weirdness.  |
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Post by snowmom on Mar 1, 2015 14:28:53 GMT -5
How did you determine Mohs? I attempted to polish a window in it with the aluminum oxide bands in my dremel moto tool, it was very slow going, took forever, and much harder than any other rocks I had polished windows in up to this point. I realize it probably has variable consistency (just look at it!) but the surface was the same in each place I tried. the sludge it made was slightly milky off white. glass won't scratch it. I have it on my list to purchase actual hardness test tools, but it hasn't happened yet.
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Post by snowmom on Mar 1, 2015 14:47:27 GMT -5
Frank (lithicbeads) on another forum finds a lot of variolite on the upper coast of Washington. It VARIES a lot. And it is not rare there because he just posted more yesterday. Jim I've got a pretty decent hoard of Variolites from local beaches. Never really done much with them except admire their "warty" weirdness. pictures please! the more the better! Jim, I have been on that website for quite a while today searching back posts for variolite! Lots of good stuff, most posted by Frank.
I have been reading and searching all day, and I have made a trip to the rock pantry. I have several other pieces as well, none of which seem as hard as this one... a few seem only a couple steps above mud. I suspect this black rock may not be completely devitirified... may have lots of silica left in it. Some sites represent these rocks as being quite fibrous in nature, so I am thinking It may be that which causes it to seem so hard. ? There are certainly way more questions than answers, and the term variolite seems to be a lot like the term jade, encompassing several different types and kinds of rock which share certain properties but can vary wildly in their makeup.
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Deleted
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Post by Deleted on Mar 1, 2015 14:51:32 GMT -5
I sent you some 6.5 mohs lavic jasper. Try scratching it with the jasper.
You alox bands may be worn. That is very subjective.
Plus the gaps between mohs are not equal.
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bcrockhound
spending too much on rocks
Member since June 2014
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Post by bcrockhound on Mar 1, 2015 17:14:01 GMT -5
Some stuff like that on Vancouver Island beaches too. Cool rock.
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Post by snowmom on Mar 1, 2015 18:00:44 GMT -5
I sent you some 6.5 mohs lavic jasper. Try scratching it with the jasper. You alox bands may be worn. That is very subjective. Plus the gaps between mohs are not equal. will go dig out the jasper, yeah, I know, pretty darn unscientific guestimate on my part. That jasper will end up in my test tools, thank you! (results pending)
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Fossilman
Cave Dweller 
Member since January 2009
Posts: 20,718
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Post by Fossilman on Mar 1, 2015 19:45:20 GMT -5
That is a nice one too!
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Post by headfullofrocks on Mar 1, 2015 23:22:42 GMT -5
In regards to your Variolite, here on Vancouver Island, we call it Dallasite. The rock around here has some variations in colors, but the idea is the same. You would see a fair amount of it around the northwest coast beaches as well as on the east side of Vancouver island. People have also been finding it around the fresh water lakes and rivers on the island. It's due to all the upthrusts of tectonic plates around this side of the Pacific ocean. Quite a few of the Lapidary guys have been polishing up beautiful cabs with it.
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bcrockhound
spending too much on rocks
Member since June 2014
Posts: 418
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Post by bcrockhound on Mar 2, 2015 23:08:05 GMT -5
In regards to your Variolite, here on Vancouver Island, we call it Dallasite. The rock around here has some variations in colors, but the idea is the same. You would see a fair amount of it around the northwest coast beaches as well as on the east side of Vancouver island. People have also been finding it around the fresh water lakes and rivers on the island. It's due to all the upthrusts of tectonic plates around this side of the Pacific ocean. Quite a few of the Lapidary guys have been polishing up beautiful cabs with it. Hey, welcome! I'm from the island but gone now. I don't think the rock above is Dallasite, though it may have some similar parts. Similar rock is on the island though, along with Dallasite. Glad you joined. |
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Post by snowmom on Mar 5, 2015 8:12:34 GMT -5
Master Shotgunner, it got to 20 degrees in my rock pantry garage the other day and I dug out the lavic jasper. Even using hard pressure and sawing at it, it left only marks about 1/2 the thickness/depth of a human hair. So... still pretty hard for what variolite is purported to be. I suppose there are all degrees of decomposition and I just got one a little less degraded.  |
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Deleted
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Post by Deleted on Mar 6, 2015 0:14:34 GMT -5
Master Shotgunner, it got to 20 degrees in my rock pantry garage the other day and I dug out the lavic jasper. Even using hard pressure and sawing at it, it left only marks about 1/2 the thickness/depth of a human hair. So... still pretty hard for what variolite is purported to be. I suppose there are all degrees of decomposition and I just got one a little less degraded. I suspect most of you glacial stuff is as tuff as it gets. Its why you aren't finding serpentine. Do you find marble? I wonder how big THAT started if it still exists. |
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Post by snowmom on Mar 6, 2015 5:00:32 GMT -5
Tandl has commented that I probably have calcite replacement rocks, silicated marble, if you will. I don't find much that is soft here, I do find what looks like serpentine, but it is pretty hard, not jade yet, but perhaps on its way. We have calcite quarries all over in Michigan, so its out there! I haven't been looking for it, but I will keep my eyes open when hunting time begins again. Won't be long now, next week is predicted to be over freezing for a day or two. A heat wave!
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Post by headfullofrocks on Mar 6, 2015 20:51:23 GMT -5
In regards to your Variolite, here on Vancouver Island, we call it Dallasite. The rock around here has some variations in colors, but the idea is the same. You would see a fair amount of it around the northwest coast beaches as well as on the east side of Vancouver island. People have also been finding it around the fresh water lakes and rivers on the island. It's due to all the upthrusts of tectonic plates around this side of the Pacific ocean. Quite a few of the Lapidary guys have been polishing up beautiful cabs with it. Hey, welcome! I'm from the island but gone now. I don't think the rock above is Dallasite, though it may have some similar parts. Similar rock is on the island though, along with Dallasite. Glad you joined. Thanks for the welcome. : ) , Please, don't misunderstand my comment. I did not mean to say that it was Dallasite, I was trying to point out the similarities as far as combinations of different minerals. As for what it's made of....Don't have the foggiest idea. One of the reasons I joined this site was to learn. |
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Post by snowmom on Mar 7, 2015 6:33:20 GMT -5
headfullofrocks, bcrockhound and washingtonrocks and I have found that many of the things we pick up in our own areas look similar to each others' finds. I think it is because it is all material from the Canadian Shield. Check out our back posts and see if the stuff you find resembles some of ours. I love comparing notes. Glad you are with us!
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Post by headfullofrocks on Mar 10, 2015 22:29:54 GMT -5
Thx again guys. glad to be among you! the next time i get out, i'll pick up some dallasite and post the pics. The dallasite here, as bcrockhound would know, seems to be primarily mixed with reddy brown and green feldspar with streaks of white/grey quartz ( chert? ), which would probably explain why the lapidary guys have such success cabbing it. and would variolite be a generic tag given to an unknown?, ( various minerals ).
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Skramblurr
off to a rocking start
You can't polish a turd
Member since December 2023
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Post by Skramblurr on Dec 30, 2023 2:02:35 GMT -5
Anyone had any luck polishing variolitic basalt in a rock tumbler? it seems the gray/green groundmass is softer than the white-ish varioles. I've tried tumbling them a few times, but without positive results. Perhaps it's a job for the Dremel... thoughts?
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